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ANIMAL  COMMUNITIES  IN  TEMPERATE 
AMERICA 


THE  UNIVERSITY  OF  CHICAGO  PRESS 
CHICAGO,  ILLINOIS 


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THE  CAMBRIDGE  UNIVERSITY  PRESS 

LONDON  AND  EDINBDRGH 

THE  MARUZEN-KABUSHIKI-KAISHA 

TOKYO,  OSAKA,  KYOTO 

KARL  W.  HIERSEMANN 

LEIPZIG 

THE  BAKER  &  TAYLOR  COMPANY 

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THE  GEOGRAPHIC  SOCIETY  OF  CHICAGO 
Bulletin  No.  5 


ANIMAL   COMMUNITIES    IN 
TEMPERATE  AMERICA 

AS   ILLUSTRATED   IN  THE 
'       CHICAGO  REGION 

A  STUDY  IN  ANIMAL  ECOLOGY 


VICTOR  E.  SHELFORD,  Ph.D. 

of  the  Department  of  Zoology 
The  Uni'versity  of  Chicago 


PUBLISHED    FOR  THE  GEOGRAPHIC  SOCIETY   OF  CHICAGO 

BY 

THE  UNIVERSITY  OF  CHICAGO  PRESS 
CHICAGO,  ILLINOIS 


Copyright  1913  By 
The  Geographic  Society  of  Chicago 


All  Rights  Reserved 


Published  October  IQI3 


Composed  and  Printed  By 

The  University  of  Chicagfo  Press 

Chicago,  Illinois,  U.S.A. 


PREFACE 

Courses  in  field  zoology  usually  lack  the  convenient  background  of 
organization  which  one  finds  in  the  doctrine  of  evolution  when  presenting 
the  animal  series  from  a  structural  standpoint.  The  need  of  some 
logical  and  philosophical  background  for  the  organization  of  natural 
history  instruction  into  something  more  unified  than  haphazard  dis- 
cussions of  such  animals  as  were  encountered  in  chance  localities,  was 
keenly  felt  at  the  beginning  of  the  author's  experience  as  a  teacher  of 
field  zoology.  Evolutionary  background  was  tried,  but  failed  and  was 
rejected;  genetics  and  faunistics  proved  inadequate.  Behavior  as 
presented  and  studied  by  zoologists  was  incomplete.  Plant  ecological 
methods  were,  when  unadapted,  applicable  only  in  part,  while  much 
of  physiology  dealt  with  organs  and  internal  processes. 

The  organization  of  the  data  here  presented  is  the  result  of  many 
attempts  and  failures  which  at  times  made  the  task  seem  hopeless.  The 
literature  relating  to  this  subject  has  been  written  almost  exclusively 
from  points  of  view  which  are  very  different  from  the  one  here  presented. 
It  is  scattered,  and  the  bibliography  has  never  been  brought  together. 
Accordingly  its  incorporation  here  has  called  for  the  expenditure  of 
much  time,  and  often  for  reinterpretation,  which  is  always  fraught  with 
danger  of  error.  The  time  consumed  in  working  over  the  literature  has 
been  great,  but,  for  the  reason  stated,  the  amount  covered  has  been  rela- 
tively small,  and  the  literature  in  foreign  languages  has  not  received  its 
share  of  attention.  Furthermore,  since  the  bulletin  is  not  written 
primarily  for  investigators,  much  of  the  literature  not  in  English  has 
been  omitted  from  the  Bibliography  but  some  of  it  will  be  found  in  the 
papers  cited.  To  present  such  a  subject  as  we  have  before  us  without 
constant  reference  to  the  writings  of  such  naturalists  as  Buffon,  White, 
Darwin,  Wallace,  Bates,  Belt,  Hudson,  Romanes,  Audubon,  Brehm, 
Fabre,  Claude  Bernard,  Huber,  Giard,  Forel,  Schmarda,  Janet,  Haase, 
Mobius,  Dahl,  and  others  (35a)  seems  at  first  thought  quite  unjustified, 
but  a  complete  study  of  the  works  of  such  men  would  be  almost  a  life's 
work  in  itself.  The  writer  does  not  claim  to  have  a  detailed  knowledge 
of  all  the  articles  written  by  these  men.  He  knows  them  only  in  part. 
Their  facts,  in  so  far  as  they  are  known  to  him  and  relate  to  the  questions 
at  hand,  tend  to  support  the  main  contentions.  But  the  successful 
organization  of  such  a  subject  depends  more  upon  the  investigation  of 


vi  ANIMAL  COMMUNITIES 

the  particular  species  and  localities  covered  than  upon  work  done  from 
different  points  of  view  in  remote  localities.  This  bulletin  is  not  intended 
as  a  textbook.  Several  years  of  work  would  be  necessary  to  give  it  the 
completeness  and  form  which  a  textbook  should  have,  and  the  physiology 
which  should  be  included  in  such  a  textbook  is  almost  entirely  omitted. 

The  organization  here  presented  has  in  the  main  grown  out  of  three 
lines  of  thought:  (a)  the  physiology  of  organisms  as  opposed  to  the 
physiology  of  organs  (51)';  (b)  the  phenomena  of  behavior  and  physi- 
ology, as  illustrated  by  the  studies  of  Loeb  (72),  much  of  the  data  of 
which  can  be  related  to  natural  environments;  and  (c)  the  organized 
comparable  data  of  plant  ecology,  as  set  forth  by  Cowles  (58)  and 
Warming  (12).  The  results  of  these  five  years  of  labor  will  not  be 
pleasing  to  many  zoologists  because  the  principles  of  evolution,  heredity, 
etc.,  have  not  been  correlated.  Their  omission,  however,  has  not  been 
due  to  any  preiudice  against  their  introduction,  but  rather  to  the  fact 
that  they  can  only  occasionally  be  related  to  this  line  of  organization. 
It  was  thought  also  that  the  complexity  of  the  problems  and  concepts 
here  treated  made  separation  a  necessity  to  clearness. 

The  number  of  problems  thrown  open  by  the  investigation  is  infinite. 
Naturalistic  observation  and  survey  work  could  be  carried  much  farther 
along  the  lines  here  blocked  out.  The  chief  lesson  which  the  author  has 
drawn  from  his  labors  is  that  experimental  study,  conducted  with  due 
reference  to  the  relations  of  the  animals  to  natural  environments,  with 
conditions  carefully  controlled,  and  a  single  factor  varied  at  a  time,  is 
one  of  the  stepping-stones  to  future  progress.  We  are  confronted  with 
centuries  of  animal  and  human  geography,  with  only  inference  or  specu- 
lation as  to  controlling  factors  for  a  background,  and  the  experimental 
study  of  factors  in  the  case  of  man  and  other  land  animals  only  at  its 
beginnings.  Though  man  is  a  land  inhabitant,  all  the  best  work  along 
these  and  many  other  lines  has  been  done  upon  aquatic  animals.  The 
writer's  course  in  the  future  will  probably  be  determined  by  the  needs 
of  the  science,  and  will  be  turned  from  the  purely  naturalistic  method 
of  study  to  a  method  made  up  of  naturalistic  observations  and  con- 
trolled experiments. 

In  undertaking  a  new  line  of  work,  one  must  have  first,  inspiration, 
next,  method  and  motive,  and  finally,  in  the  case  of  ecological  work,  the 
assistance  of  a  large  number  of  persons  in  various  departments  of 
knowledge.     For  such  assistance  I  wish  to  express  my  indebtedness  to 

'  Numbers  in  parentheses,  scattered  through  this  work,  refer  to  references  in  the 
Bibliography  at  the  end  (pp.  325-36). 


PREFACE  vii 

the  following:  to  Professor  C.  M.  Child,  of  the  University  of  Chicago, 
for  my  first  serious  inspiration  in  natural  history,  and  for  my  oppor- 
tunity to  develop  ecology;  he  has  also  rendered  important  assistance 
in  connection  with  the  preparation  of  this  work,  by  giving  information 
regarding  animals  about  Chicago;  his  assistance  with  the  worms  and 
other  lower  invertebrates  has  been  of  particular  importance;  to  Dr.  H.  C. 
Cowles,  of  the  University  of  Chicago,  for  constant  assistance  with  the 
plants  and  all  matters  relating  to  plant  ecology.  Various  graduate 
students  and  assistants  at  the  University  of  Chicago  have  also  aided 
materially  in  the  preservation  of  notes,  specimens,  and  records.  Mr. 
Beniah  H.  Dimmot,  Dr.  W.  C.  AUee,  Mr.  G.  D.  Men,  Mr.  S.  S.  Visher, 
and  Mr.  M.  M.  Wells  should  be  mentioned  especially.  Mabel  Brown 
Shelford  collected  the  data  on  the  former  occurrence  of  animals  now 
extinct,  and  on  other  historical  matters. 

The  following  have  furnished  identifications  and  important  advice 
in  connection  with  the  various  groups  in  which  they  are  specialists: 

Dr.  N.  A.  Harvey,  Ypsilanti,  Mich.,  Sponges. 

Dr.  R.  C.  Osburn,  Columbia  University,  Polyzoa. 

Dr.  J.  P.  Moore,  University  of  Pennsylvania,  Leeches. 

Mr.  F.  C.  Baker,  Chicago  Academy  of  Sciences,  Mollusca. 

Dr.  C.  D.  Marsh,  U.S.  Department  of  Agriculture,  Copepods. 

Mr.  Richard  W.  Sharpe,  Brooklyn  Institute,  Ostracoda. 

Dr.  Chauncey  Juday,  University  of  Wisconsin,  Cladocera. 

Dr.  E.  A.  Ortmann,  Carnegie  Museum,  Crayfishes. 

Miss  A.  L.  Weckel,  Oak  Park,  111.,  Amphipods. 

Miss  Harriet  Richardson,  U.S.  National  Museum,  Isopods. 

Mr.  O.  F.  Cook,  U.S.  Department  of  Agriculture,  Myriopods. 

Dr.  R.  H.  Wolcott,  University  of  Nebraska,  Water  Mites. 

Mr.  Nathan  Banks,  U.S.  Department  of  Agriculture,  Spiders. 

Mr.  C.  A.  Hart,  University  of  Illinois.     All  groups  of  insects. 

Dr.  J.  G.  Needham,  Cornell  University,  Aquatic  insects. 

Dr.  Cornelius  Betten,  Lake  Forest  University,  Caddis-flies. 

Mr.  W.  J.  Gerhard,  Field  Museum,  Hemiptera  and  general  entomology. 

Mr.  A.  B.  Wolcott,  Field  Museum,  Beetles. 

Prof.  H.  F.  Wickham,  University  of  Iowa,  Beetles. 

Dr.  Joseph  Hancock,  Chicago,  Orthoptera. 

Mr.  W.  S.  Blatchley,  Indianapolis,  Orthoptera. 

Dr.  A.  D.  MacGillivray,  University  of  Illinois,  Sawflies  and  insect  larvae. 

Dr.  S.  E.  Meek  and  Mr.   S.   F.  Hildebrand,  Field  Museum,  Vertebrates. 

Mr.  Alexander  Kwiat,  Chicago,  Lepidoptera. 

Miss  Clara  Cunningham,  South  Bend,  Tamarack  Swamps. 

Dr.  Frank  Smith,  University  of  Illinois,  Annelids. 


viii  ANIMAL  COMMUNITIES 

Mr.  S.  S.  Visher  and  Mr.  Ralph  Chaney  contributed  most  of  the  habitat  data 
on  birds.  Dr.  R.  M.  Strong  verified  those  included  here  which  were 
also  compared  with  Butler's  account  (io8).  T.  C.  Stephens  supplied  the 
photographs  of  nests. 

Dr.  P.  G.  Heinemann,  University  of  Chicago,  Bacteria. 

Dr.  Susan  P.  Nichols,  Oberlin  College,  Algae. 

Mrs.  Elva  Class  and  Mr.  M.  M.  Wells  of  the  University  of  Chicago,  and  Dr. 
W.  C.  AUee,  of  the  University  of  Illinois,  Gas  analysis. 

Mariner  and  Hoskins,  Commercial  Chemists,  Analysis  of  Water. 

The  original  records  upon  which  the  work  is  largely  based  could  not 
all  be  presented.  Those  placed  at  the  end  of  the  chapters  are  believed 
to  be  representative,  in  that  they  include  some  characteristic  animals, 
some  which  are  numerous  but  occur  elsewhere  also,  and  some  of  wide  dis- 
tribution. The  records  in  the  text  are  also  largely  original,  except  in  the 
case  of  mammals,  the  habitat  locations  of  which  are  based  upon  literature. 
Mr.  W.  H.  Osgood  of  the  Field  Museum  has  assisted  in  the  editing  of  the 
data  on  mammals.  Original  records  in  this  group  are  especially  indicated. 
Data  on  the  nesting  habits  of  birds  have  likewise  depended  upon  compila- 
tion, though  the  locality  records  are  those  of  the  persons  mentioned. 
Mr.  W.  S.  Stahl,  assistant  United  States  attorney,  edited  the  paragraphs 
on  the  legal  restrictions  upon  field  study  and  collection  of  animals. 

The  matter  of  scientific  names  is  one  presenting  unusual  diflSculties 
because  of  the  scattered  and  incomplete  character  of  catalogues.  The 
work  of  identification  having  occupied  several  years^  changes  in  nomen- 
clature may  have  led  to  some  confusion  and  duplication  of  records  under 
different  names.  The  matter  of  correcting  spelling  is  unusually  difficult 
because  of  numerous  works  which  it  is  necessary  to  consult  for' verification 
in  dealing  with  representatives  of  nearly  all  groups  from  Protozoa  to 
mammals.  The  specialists  on  the  different  groups  have  been  very  kind 
in  answering  any  question,  but  the  final  responsibility  rests  with  the 
author.  In  the  main  the  nomenclature  in  the  following  works  has 
been  followed  (numbers  refer  to  Bibliography  at  the  end  of  this  work) : 
mammals,  21;  birds,  108;  reptiles,  157,  157a;  Amphibia,  139  and  152; 
fishes,  79;  flies,  Aldrich's  ('00)  Catalogue  (N.A.);  beetles,  156  and 
Samuel  Henshaw's  ('85)  checklist;  Hemiptera  (Heteroptera),  Bank's  ('11) 
Catalogue;  aquatic  insects,  95  and  96;  ants,  54;  insects  not  included 
in  the  special  lists,  177;  Hymenoptera  not  in  177,  E.  T.  Cresson's  ('87) 
Synopsis;  spiders,  159;  PZra^c«g7'(/ce  and  land  mites,  172  and  184;  water- 
mites,  149;  myriopods,  183;  moUusks,  F.  C.  Baker's  ('06)  Catalogue 
for  Illinois;  leeches,  910;  crayfishes,  loi,  loia;  amphipods,  102;  isopods, 


PREFACE  ix 

182;  copepods,  146,  1460;  ostracods,  147;  other  Entomostraca,  Herrick 
and  Turner's  ('95)  synopsis  for  Minnesota. 

In  the  case  of  several  names  not  included  in  any  of  these  works  there 
are  contradictory  spellings,  authors,  etc.,  and  we  have  used  some  name 
which  we  believe  will  be  understood. 

In  bringing  together  the  illustrations,  material  assistance  has  been 
rendered  as  follows: 

Dr.  S.  W.  Williston,  loan  of  Figs.  30,  31,  32,  126,  132,  174,  186,  187,  188,  210, 
267,  269,  270,  271,  272,  273,  274,  275,  282,  283,  284,  285,  286,  from  his 
Manual  of  North  American  Diptera. 

Dr.  F.  R.  Lillie  and  the  Biological  Bulletin,  loan  of  Figs.  66,  67,  68,  69,  83,  84, 
85,  loi,  251,  252,  253,  previously  published  by  the  author  in  the  Biological 
Bulletin. 

Professor  S.  A.  Forbes,  the  Illinois  State  Laboratory,  and  the  State  Ento- 
mologist's Office,  loan  of  Figs.  35,  36,  44,  45,  46,  and  72,  which  appeared  in 
Vol.  Ill  of  the  Natural  History  Survey  of  Illinois,  and  for  electrotypes  of 
Figs.  261,  262,  264,  265,  288,  289,  290,  291,  292,  296,  297, 301,  302,  303,  304, 
305,  306,  which  appeared  originally  in  the  Annual  Reports  and  Bulletins 
of  the  State  Entomologist  and  other  state  and  national  publications. 

Professor  S.  E.  Meek  and  the  Field  Museum,  loan  of  Fig.  37. 

Professor  J.  M.  Coulter  and  the  Botanical  Gazette,  loan  of  Fig.  115. 

Professor  F.  L.  Washburn  and  the  Minnesota  State  Entomologist's  Office  for 
electrotypes  of  Figs.  136,  137,  156,  189,  194,  211,  212,  213,  229,  256,  263, 
266,  268,  276,  277,  278,  293,  298,  299,  300. 

Professor  Vernon  L.  Kellogg,  privilege  of  using  Figs.  18S,  270,  271,  274  from 
North  American  Insects,  which  appear  also  in  Williston's  Manual  of 
North  American  Diptera. 

Professor  J.  H.  Emerton,  privilege  of  using  Figs.  207,  208,  224,  225  fromCom- 
mon  Spiders. 

Figures  after  Lugger  appeared  originally  in  Bulletins  55,  66,  and  6q  and  the 
Fourth  Annual  Report  of  the  Minnesota  Agricultural  Experiment  Station. 

Figures  after  Marlatt,  Riley,  and  Chittenden  appeared  originally  in  publica- 
tions of  the  U.S.  Department  of  Agriculture;  after  Gorham,  Smith, 
Jennings,  and  Reighard,  in  publications  of  the  U.S.  Fish  Commission. 

The  author  is  also  indebted  to  Dr.  J.  P.  Goode,  Dr.  Otis  W.  Caldwell, 
Dr.  H.  C.  Cowles,  Professor  R.  D.  Salisbury,  Professor  C.  M.  Child, 
and  Mr.  M.  M.  Wells  for  assistance  in  editing  the  manuscript  and  read- 
ing proof.  Mr.  W.  J.  Gerhard  rendered  special  assistance  in  the  reading 
of  the  proof  of  the  scientific  names. 

It  is  evident  from  the  number  of  persons  who  have  assisted  in  the 
working  over  of  material  and  the  accumulation  of  the  data  on  which  this 


ANIMAL  COMMUNITIES 


work  is  based,  that  the  survey  aspect  of  ecology  is  a  subject  for  co- 
operative investigation.  Because  of  the  complexity  of  the  problems,  it 
has  been  deemed  advisable  to  publish  this  work  even  in  its  present 
preliminary  and  necessarily  incomplete  form,  in  order  to  make  the 
material  accessible  as  soon  as  possible  to  teachers,  investigators,  and 
others  who  are  interested. 


Department  of  Zoology 

University  of  Chicago 

September  9,  19 12 


TABLE   OF   CONTENTS 

PAGE 

Introduction i 

CHAPTER 

I.    Man  and  Animals 5 

I.    Introduction 5 

II.    The  Struggle  in  Nature 6 

III.  Man's  Relation  to  Nature 8 

IV.  The  Economic  Importance  of  Animals 20 

II.    The  Animal  Organism  and  Its  Environmental  Relations  22 

I.    Nature  of  Living  Substance 22 

II.    The  Relation  of  Form  or  Structure  to  Function  ....  22 

III.  The  Basis  for  the  Organization  of  Ecology 23 

IV.  Scope  and  Meaning  of  Ecology 32 

V.     Communities  and  Biota 33 

III.  The  Animal  Environment:    Its  General  Nature  and  Its 
Character  in  the  Area  of  Study 42 

I.    Nature  and  Classification  of  Environments 42 

II.    The  Important  Factors  and  Their  Control  in  Nature  43 

III.  History  of  the  Region  about  Lake  Michigan       ....  44 

IV.  Extent  and  Topography  of  the  Area  Considered       ...  48 
V.    Climate  and  Vegetation  of  the  Area          49 

VI.    Localities  of  Study  (Guide) 50 

VII.    Legal  Aspects  of  Field-Study 56 

IV.  Conditions  of  Existence  of  Aquatic  Animals      ....  58 

I.    Introduction:    Comparison  of  Land  and  Aquatic  Animals  58 

II.     Chemical  Conditions 58 

III.  Physical  Conditions 60 

IV.  Elementary  Food  Substances 65 

V.    Quantity  of  Life  in  Water 67 

V.    Animal  Communities  of  Large  Lakes  (Lake  Michigan)  73 

I.    Conditions ^3 

II.     Communities  of  the  Lake 73 

III.    Summary 81 

VI.    Animal  Communities  of  Streams 86 

I.    Introduction 86 

II.    Communities  of  Streams 86 

III.    Special  Stream  Problems 105 

xi 


xii  ANIMAL  COMMUNITIES 

CHAPTER  PAGE 

VII.    Animal  Communities  of  Small  Lakes 124 

I.    Introduction 124 

II.    Communities  of  Small  Lakes 125 

III.    Succession  in  Lakes 133 

VIII.    Animal  Communities  of  Ponds 136 

I.    Introduction 136 

II.    Area  of  Special  Study 136 

III.  Communities  of  Ponds 140 

IV.  Succession 151 

IX.    Conditions  of  Existence  of  Land  Animals 157 

I.    Introduction 157 

II.    SoU 157 

III.  Atmosphere 159 

IV.  Combinations  or  Complexes  of  Factors 161 

V.    Quantity  of  Life  on  Land 166 

X.    Animal  Communities  of  the  Tension  Lines  between  Land 

AND  Water       ..." 169 

I.    Introduction 169 

II.    Communities 169 

III.    General  Discussion 183 

XI.    Animal  Communities  of  Swamp  and  Flood-Plain  Forests  189 

I.    Introduction 189 

II.    Swamp  Forest  Formations  and  Associations 189 

XII.    Animal  Communities  of  Dry  and  Mesophytic  Forests  209 

I.    Introduction 209 

II.    Forest  Communities  on  Clay 209 

III.  Forest  Communities  on  Rock         217 

IV.  Forest  Communities  on  Sand    . 218 

V.    Mesophytic  Forest  Formation 233 

VI.    General  Discussion 247 

XIII.  Animal  Communities  of  Thickets  and  Forest  Margins     .  262 

I.    Introduction         262 

II.    Low  Forest  Margin  Sub-Formations 262 

III.  High  Forest  Margin  Sub-Formations 268 

IV.  General  Discussion 274 

XIV.  Prairie  Animal  Communities 278 

I.    Introduction 278 

II.    Prairie  Formations .278 

III.    General  Discussion 295 


CONTENTS 


CHAPTER 


PAGE 


XV,    General  Discussion 299 

I.    Introduction 299 

II.    Application  of  the  Laws  Governing  Animal  Activities  to 

World  and  Regional  Problems 299 

III.  Agreement  between  Plants  and  Animals 304 

IV.  Relations  of  Communities 308 

V.    General  Relation  of  Communities  of  the  Same  Climate  311 

VI.    Relations  of  Ecology  to  Other  Biological  Subjects    .  315 

VII.    Relations  of  Ecology  to  Geography 318 

Appendix:  Methods  of  Study 321 

Bibliography ^25 

Index  of  Authors  and  Collaborators 330 

Index  of  Subjects 343 


INTRODUCTION 

Just  at  the  beginning  of  the  present  century,  there  seems  to  have 
been  a  revival  of  interest  in  plants  and  animals  in  relation  to  their 
environments,  and  various  workers  have  turned  from  the  study  of 
anatomy  and  classification  in  the  laboratory  to  the  study  of  organisms  in 
nature.  In  this,  the  botanists  have  preceded  the  zoologists,  in  success 
if  not  in  time.  In  1901  Dr.  H.  C.  Cowles  published  a  bulletin  on  the 
Plant  Societies  of  the  Chicago  Area.  This  was  one  of  the  first  attempts  of 
an  American  biologist  to  treat  all  the  plants  of  a  given  area  in  a  strictly 
ecological  manner.  This  study  of  all  the  organisms  of  an  area,  from  the 
point  of  view  of  their  relations  to  each  other  and  to  their  environment, 
is  still  a  new  or  at  least  a  renewed  idea.  Zoologists  have  devoted  most 
of  their  attention  to  the  study  of  animals  from  the  standpoint  of  a  single 
individual  and  of  single  species.  Practically  all  of  the  more  general 
study  has  been  comparative.  We  have  comparative  anatomy,  compara- 
tive embryology,  comparative  physiology,  and  comparative  psychology. 
These  are  comparisons  of  the  structure  or  physiology  of  one  species,  or 
group  of  species,  with  that  of  another  species  or  group  of  species. 

Our  point  of  view  is  very  different.  We  shall  deal  with  many  species 
from  the  standpoint  of  their  dependence  upon  each  other  and  their 
relations  to  their  environments.  We  shall  attempt  to  present  what  has 
been  learned  upon  this  subject  during  several  years  of  investigation  and 
field  teaching.  In  the  spring  of  1903,  the  writer  made  his  first  field 
excursion  in  the  Chicago  area,  and  from  that  time  has  been  engaged  in 
further  study  of  the  subject. 

The  study  of  organisms  in  relation  to  environment  is  entitled  ecology. 
The  definition  of  ecology,  like  that  of  any  growing  science,  is  a  thing  to 
be  modified  as  the  science  itself  is  modified,  crystallized,  and  limited.  At 
present,  ecology  is  that  branch  of  general  physiology  which  deals  with  the 
organism  as  a  whole,  with  its  general  life  processes,  as  distinguished  from 
the  more  special  physiology  of  organs  (51),  and  which  also  considers  the 
organism  with  particular  reference  to  its  usual  environment. 

Undertaking  such  a  study  from  the  point  of  view  of  many  organisms 
involves  matters  of  both  ecological  and  taxonomic  classification.  Classi- 
fication of  animals  is  difl&cult  because  animals  are  so  exceedingly  numer- 
ous. There  are  probably  from  10,000  to  20,000  species  of  animals  which 
the  naturalist  may  encounter  in  the  area  which  we  are  treating,  while 


2  ANIMAL  COMMUNITIES 

in  the  same  area  the  botanist  would  probably  find  only  about  2,000 
conspicuous  plant  species.  Representatives  of  all  animal  species  must 
be  submitted  to  specialists  for  identification,  ^hat  is,  the  specialist 
gives  the  correct  scientific  name  to  the  animal.  Scientific  names  are 
definitely  arranged  as  below,  if  man  is  taken  as  an  example. 

Phylum  -         -        -         -        Chordata  or  Vertebrata 

Class  ------  Mammalia 

Order  ------  Primates 

Family  ------         Hominidae 

Genus  -        -        -        -        -        -        -         Homo 

Species  -------      sapiens 

The  young  of  many  insects  and  of  some  other  animals  cannot  be 
placed  in  the  proper  species  because  animal  life  histories  are  very  imper- 
fectly known.  Such  animals  are  merely  placed  in  the  proper  genus  or 
family.  The  common  names  of  animals  rarely  apply  to  single  species 
but  to  whole  genera,  families,  or  even  orders.  "  Caddis-worm  "  is  a  name 
applied  to  a  whole  order  of  insect  larvae  and  as  these  are  very  imper- 
fectly known  the  term  caddis-worm  is  applied  to  many  species,  and, 
applied  in  this  way,  appears  in  many  places  in  the  text. 

Because  of  the  large  number  of  animals  and  the  difficulty  in  naming 
them,  it  is  quite  impossible  to  deal  with  the  data  in  the  specific  way  that 
might  be  possible  with  plants.  Furthermore,  while  the  data  for  plant 
distribution  are  not  well  known,  those  for  animal  distribution  are  much 
less  well  known.  Therefore  in  most  cases  it  is  necessary  to  speak  in 
general  terms.  It  is  impossible  and  undesirable  to  discuss  each  com- 
munity of  animals  in  detail.  The  facts  are  not  known,  and  even  if  they 
were  known,  their  volume  would  be  such  as  to  exclude  the  great  majority 
of  them  from  the  limits  of  this  treatise.  In  most  cases  it  is  best  to  make 
a  statement  of  the  leading  facts,  and  a  few  statements  about  the  specific 
situations  to  give  an  idea  of  the  kinds  of  animals  that  are  characteristic 
or  common  there.  It  should  be  noted  also  that  the  most  characteristic 
animals  are  often  not  generally  known  and  are  in  some  cases  rare. 

The  scientific  names  of  characteristic  and  common  animals  are 
included,  not  so  much  for  geographers  at  present,  as  to  form  a  basis  for 
further  work  and  comparison  by  zoologists  and  zoogeographers.  Where 
given  in  the  form  of  tables  they  present  the  actual  scientific  background 
for  the  facts  here  stated.  Much  greater  detail  would  be  needed  for  a 
full  zoological  treatment.  Scientific  names  are  usually  used  where  the 
common  names  apply  to  many  species.  The  names  of  authors  of  species 
are  added  in  the  text  and  description  of  figures  only  where  they  do  not 


INTRODUCTION  3 

appear  in  either  the  lists  and  tables  or  in  the  descriptions  of  figures.  No 
attempt  has  been  made  to  include  the  same  animals  in  the  text,  tables, 
and  illustrations,  as  the  only  aim  has  been  to  make  each  part  as  useful 
as  possible. 

While  the  amount  of  work  that  might  have  been  done  along  the  lines 
here  represented  is  infinite,  this  work  represents  only  a  general  survey. 
The  data  are  incomplete,  but  we  believe  them  to  be  adequate  for  the 
purpose  of  illustrating  the  principles  involved.  Considerable  experi- 
mental work  has  been  conducted  with  reference  to  animal  communities,' 
but  it  has  served  only  as  a  background,  and  in  comparing  them  we 
have  relied  upon  comparison  of  (a)  habitats  and  {h)  species.  The  latter 
is  fraught  with  many  dangers,  for  it  assumes,  in  the  absence  of  evidence 
to  the  contrary,  that  the  physiological  character  of  a  species  is  the  same 
in  the  different  situations  in  which  it  is  taken.  Observation  has  shown 
this  to  be  true  for  most  species  within  rather  uncertain  limits.  There 
are,  however,  many  well-known  exceptions  to  this,  some  of  which  are  cited 
in  the  text.  Such  use  of  species  is  certainly  to  be  avoided  in  the  study 
of  the  extensive  or  geographic  distribution  of  animals,  and  it  remains 
to  be  seen  how  far  it  may  be  employed  locally.  Certainly  ecology  cannot 
reach  its  best  development  if  it  relies  upon  such  a  method.  Whatever 
further  investigation  may  prove  on  this  point,  it  is  hoped  at  least  that 
we  may  be  ablo  to  suggest  problems  which  may  be  attacked  from  new 
points  of  view.  Should  this  object  be  accomplished,  the  work  will  have 
served  its  purpose. 

'The  term  community,  as  used  here,  refers  to  all  the  animals  living  in  the  same 
surroundings. 


CHAPTER  I 

MAN  AND  ANIMALS 
I.    Introduction 

I.      CULTURE   AND   NATURE 

In  this  discussion  we  are  concerned  with  nature  and  our  relations  to 
nature. 

Nature  is  an  enormous  aggregation  of  things — objects — each  having  cer- 
tain metes  and  bounds,  certain  quahties  and  powers,  beyond  which  it  cannot 
go.  Now,  knowledge  of  nature,  sanity  toward  nature,  consists  exactly  not  only 
in  ever  increasing  the  extent  of  our  inventory  of  these  objects,  but  of  recog- 
nizing, without  addition  or  subtraction,  that  is,  accurately  and  justly,  the 
forms,  the  qualities,  and  the  forces  of  these  objects — what  they  are  and  what 
they  are  not;  what  they  can  do  and  what  they  cannot  do. 

Is  there  anything  worse  than  mild  folly  in  the  belief  in  the  "sea  serpent"  ? 
That  depends.  If  the  belief  involves  the  notion  "monster,"  then  yes,  decidedly, 
for  the  belief  is  of  the  self-same  kind  that  has  prevented  men  from  being  sane, 
that  has  filled  them  with  dread,  in  all  ages.  It  is  a  question,  not  of  nature,  but 
of  state  of  mind.  The  person  whose  mental  attitude  is  such  that  he  easily  and 
unwittingly  puts  into  the  sea  from  his  own  consciousness  a  creature  that  does 
not  exist  in  the  sea,  and  holds  it  to  be  as  real  as  those  that  do  exist  there,  is 
also  in  a  state  of  mind  to  attribute  to  all  sorts  of  innocent  creatures  and  persons 
qualities  and  powers  they  do  not  have  and  hold  these  powers  to  be  as  real  as 
the  ones  they  actually  do  possess. — Ritter  (i).' 

We  have  all  heard  of  the  octopus  or  devil-fish,  with  its  long  arms 
covered  with  powerful  suckers,  which  is  always  waiting  to  seize  the 
unsuspecting,  choke  and  bite  him,  always  grasping  with  another  arm 
when  the  grip  of  one  of  them  is  loosened — suitable  symbol  of  the  trust. 

A  person  wading  in  the  water  among  rocks  where  there  are  devil  fishes  is 
about  as  likely  to  be  attacked  and  bitten  by  one  of  the  animals  as  he  is  to  be 
injured  by  the  explosion  of  a  watermelon,  when  walking  through  a  melon  patch. 
Both  things  are  possible. 

The  octopus  secretes  a  great  quantity  of  black  fluid  and  makes  use  of  this 
by  squirting  it  into  the  water  to  envelop  itself  in  "pitch  darkness"  against 
the  approach  of  enemies.  But  the  fluid  is  not  poisonous,  nor  the  leastwise 
injurious  to  anybody  or  to  any  creature,  so  far  as  we  know. 

'  Numbers  in  parentheses,  scattered  through  this  work,  refer  to  references  in  the 
Bibliography  at  the  end  (pp.  325-36). 

S 


6  MAN  AND  ANIMALS 

In  short,  the  animal  is  not  a  "horrid  thing,"  as  it  is  painted  in  story  and 
in  many  a  dimly  lighted  imagination.     There  is  nothing  devilish  about  it. 

And  here  is  the  moral  of  the  "devil  fish  ":  If  there  is  a  corner  of  your  mind 
that  wants  to  attribute  to  the  octopus  malevolent  qualities  and  powers  that  it 
does  not  possess,  and  is  content  to  overlook  or  deny  to  it  qualities  and  powers 
of  interest  and  beauty  that  it  does  possess,  mark  my  word,  the  same  corner  of 
your  mind  will  tend  to  treat  such  at  least  of  your  fellow-men  as  you  do  not  know 
well,  in  the  same  way.  This  unfortunate  corner  of  your  mind  will,  like  all 
other  corners,  be  true  to  itself — to  its  own  qualities.  It  is  the  old  impossibility 
of  blowing  hot  and  blowing  cold  at  the  same  time. — Ritter  (i). 

We  may  accept  this  as  one  of  our  relations  to  nature  and  general 
culture,  and  sanity  toward  nature  as  one  of  the  benefits  to  be  derived 
from  study  of  science  and  nature. 

2.      SCIENCE   AND   NATURE 

All  biological  problems  are  problems  of  nature.  Evolution  became  a 
problem  only  when  a  large  knowledge  regarding  the  number  and  diversity 
of  animal  species  had  been  acquired.  This  has  been  the  problem  around 
which  most  zoological  facts  have  been  accumulated.  Indeed,  most 
zoologists  have  little  interest  in  problems  not  throwing  light  on  evolution. 
The  development  of  zoology  has  therefore  been  one-sided.  Had  geology 
clung  as  closely  to  the  origin  of  the  earth  as  zoology  to  evolution,  it 
would  not  be  the  unified  science  which  we  see  it  today.  The  lack  of 
unity  in  zoology  has  been  caused  in  part  by  the  neglect  of  the  aspects 
which  we  are  to  take  up  here.  In  this  connection,  Thompson  (2)  has 
said  of  Brehm,  one  of  the  older  students  of  natural  history:  " He  [Brehm ] 
had  unusual  power  as  an  observer  of  the  habits  of  animals.  His 
particular  excellence  is  his  power  of  observing  and  picturing  animal 
life  as  it  is  lived  in  nature,  without  taking  account  of  which,  biology  is 
a  mockery,  and  any  theory  of  evolution  a  one-sided  dogma."  It  follows 
also  that  sanity  in  science  is  dependent  upon  a  knowledge  of  nature. 
Our  first  steps  in  the  task  before  us  must  accordingly  be  a  consideration 
of  wild  nature  as  it  really  is.  This  can  perhaps  best  be  accomplished  by 
comparing  the  reality  with  some  of  our  conceptions  of  it. 

II.    The  Struggle  in  Nature 

The  first  step  toward  an  understanding  of  our  relation  to  nature, 
or  rather  the  animals  and  animal  communities  of  natural  conditions,  is 
to  acquire  a  knowledge  of  the  conditions  of  animals  in  a  state  of  nature. 
There  is  much  literature  on  this  subject,  but  our  conception  of  the 
struggle  for  existence  and  the  survival  of  the  fittest  is  too  often  entirely 


STRUGGLE  IN  NATURE  7 

forgotten  when  we  are  considering  our  relation  to  animals.  Nature  is 
cruel  and  heartless,  and  to  die  to  become  food  of  another  organism  is  the 
fate  of  the  vast  majority  of  animals.     Mr.  Roosevelt  has  said : 

Watching  the  game,  one  was  struck  by  the  intensity  and  evanescence  of 
their  emotions.  Civilized  man  now  usually  passes  his  life  under  conditions 
which  eliminate  the  intensity  of  terror  felt  by  his  ancestors  when  death  by 
violence  was  their  normal  end,  and  threatened  them  during  every  hour  of  the 
day  and  night.  It  is  only  in  nightmares  that  the  average  dweller  in  civilized 
countries  now  undergoes  the  hideous  horror  which  was  the  regular  and  frequent 
portion  of  his  ages-vanished  forefathers,  and  which  is  still  an  everyday  incident 
in  the  lives  of  most  wild  creatures.  But  the  dread  is  short-lived,  and  its 
horror  vanishes  with  instantaneous  rapidity.  In  these  wilds  the  game  dreaded 
the  lion  and  the  other  flesh-eating  beasts  rather  than  man.  We  saw  innumer- 
able kills  of  all  the  buck  and  of  zebra,  the  neck  usually  being  dislocated,  it 
being  evident  that  none  of  the  lion's  victims,  not  even  the  truculent  wildebeeste 
or  huge  eland,  had  been  able  to  make  any  fight  against  him.  The  game  is 
ever  on  the  alert  against  this  greatest  of  foes,  and  every  herd,  almost  every 
individual,  is  in  imminent  and  deadly  peril  every  few  days  or  nights,  and  of 
course  suffers  in  addition  from  countless  false  alarms.  But  no  sooner  is  the 
danger  over  than  the  animals  resume  their  feeding,  or  love-making,  or  their 
fighting  among  themselves.  Two  bucks  will  do  battle  the  minute  the  herd  has 
stopped  running  from  the  foe  that  has  seized  one  of  its  number,  and  a  buck 
resumes  his  love-making  with  ardor,  in  the  brief  interval  between  the  first  and 
second  alarm  from  hunter  or  lion.  Zebras  will  make  much  noise  when  one  of 
their  number  has  been  killed;  but  their  fright  has  vanished  when  once  they 
begin  their  barking  calls. 

Death  by  violence,  death  by  cold,  death  by  starvation— these  are  the 
normal  endings  of  the  stately  and  beautiful  creatures  of  the  wilderness.  The 
sentimentalists  who  prattle  about  the  peaceful  life  of  nature  do  not  realize  its 
utter  mercilessness;  although  all  they  would  have  to  do  would  be  to  look  at 
the  birds  in  the  winter  woods,  or  even  at  the  insects  on  a  cold  morning  or  cold 
evening.  Life  is  hard  and  cruel  for  all  the  lower  creatures,  and  for  man  also 
in  what  the  sentimentalists  call  a  "state  of  nature."  The  savage  of  today 
shows  us  what  the  fancied  age  of  gold  of  our  ancestors  was  really  like;  it  was 
an  age  when  hunger,  cold,  violence,  and  iron  cruelty  were  the  ordinary  accom- 
paniments of  life.  If  Matthew  Arnold,  when  he  expressed  the  wish  to  know 
the  thoughts  of  earth's  "vigorous,  primitive"  tribes  of  the  past,  had  really 
desired  an  answer  to  his  question,  he  would  have  done  well  to  visit  the  homes  of 
the  existing  representatives  of  his  "vigorous,  primitive"  ancestors,  and  to 
watch  them  feasting  on  blood  and  guts;  while  as  for  the  "pellucid  and  pure" 
feelings  of  his  imaginary  primitive  maiden,  they  were  those  of  any  meek,  cow- 
like creature  who  accepted  marriage  by  purchase  or  of  convenience,  as  a  matter 
of  course.— From  African  Game  Trails,  by  Theodore  Roosevelt;  Copyright, 
1910,  by  Charles  Scribner's  Sons  (3). 


3  MAN  AND  ANIMALS 

III.     Man's  Relation  to  Nature 

Mr.  Roosevelt's  statement  is  quite  different  from  much  of  the  poetry 
about  nature,  still  it  is  a  true  picture.  We  live  in  a  man-made  nature 
from  which  the  conspicuous  animals  and  their  deadly  struggles  have 
been  eliminated  (4,  5).  Of  the  admirers  of  the  beauties  of  nature  I 
fancy  that  many,  perhaps  the  majority,  think  of  it  as  a  series  of  lawn- 
like pastures,  well-trimmed  hedges,  such  as  finds  its  ideal  expression  in 
some  of  the  older  countries  like  England. 

The  trees,  round,  woolly,  ready  to  be  clipped; 
And  if  you  seek  for  any  wilderness 
You  find,  at  best,  a  park,  a  Nature  tamed 
And  grown  domestic  like  a  barnyard  fowl. 

— E.  B.  Browning,  "Aurora  Leigh." 

The  close  observer  of  nature,  even  in  such  man-made  conditions  as  in 
Bedfordshire  or  in  the  Chicago  parks,  sees  all  the  struggle  which  Mr. 
Roosevelt  has  depicted  for  the  birds  and  mammals  of  primeval  conditions. 
To  kill  is  nature's  first  law. 

I.  man's  conduct  toward  animals 
There  is  much  sentimental  nonsense  about  nature,  about  animals 
and  cruelty  to  animals,  as  well  as  much  actual  cruelty  and  wanton 
destruction  of  useful  animals.  With  some  people  birds  obscure  all  else 
in  the  animal  world.  The  destruction  of  squirrels,  which  are  equally  if 
not  more  interesting  than  birds,  is  sometimes  advocated  because  of  their 
alleged  destruction  of  birds'  eggs.  The  friend  of  the  squirrel  would 
plead  equally  hard  for  the  destruction  of  certain  hawks  and  owls  as 
enemies  of  the  squirrel.  Certainly  all  lovers  of  the  insect  world  might 
advocate  the  destruction  of  birds  to  protect  their  particular  zoological 
pets. 

That  birds  save  the  harvests  of  every  season  is  believed  by  many. 
The  student  of  mammals  is  equally  sure  that  certain  mammals  are  the 
balance  wheel,  while  the  herpetologist  is  convinced  of  the  importance  of 
snakes,  and  the  entomologist's  economic  world  turns  about  predatory  and 
parasitic  insects  and  spiders.  The  fact  is  that  each  view,  even  thus 
extremely  stated,  contains  its  elements  of  truth.  The  whole  truth  is 
hardly  knowable.  Each  animal  is  dependent  upon  many  others.  The 
dependences  are  so  numerous  that  we  find  it  necessary  to  isolate  par- 
ticular animals  and  construct  them  into  a  society  of  real  but  limited 
relations  for  purposes  of  discussion  (see  p.  170).  Still  there  are  a  few 
things  that  we  can  be  reasonably  sure  of.     The  first  is  that  we  cannot 


MAN  AND  NATURE  g 

interfere  with  any  animals  or  the  habitats  of  any  animals  without  inter- 
fering with  many  others.  The  second  is  that  all  animals  are  of  some 
economic  importance.  The  third,  that  few  animals  can  be  said  to  be 
either  wholly  beneficial  or  wholly  noxious,  excepting  those  reared  or 
preserved  for  their  direct  utility,  and  those  directly  and  perniciously 
attacking  the  necessities  of  man's  existence. 

Considering  the  first,  we  note  that  civilized  man's  operations  interfere 
with  animals  and  animal  habitats.  His  first  work  is  to  destroy  all  large, 
dangerous  animals.  He  clears  and  cultivates  the  land,  bringing  death 
and  destruction  to  many  more,  and  gradually  substitutes  domestic  ani- 
mals for  wild  game  (5a).  Vegetarians  often  argue  for  the  exclusive  use 
of  vegetable  food  on  the  ground  that  animals  should  not  be  killed,  but 
to  secure  more  plants  for  this  purpose  they  of  necessity  would  clear  more 
land  to  grow  more  corn  and  thus  destroy  myriads  of  animals  by  methods 
more  cruel  than  those  of  the  butcher  and  huntsman.  Our  relations  to 
animals  are  not  simple,  but  very  complex  and  our  conduct  often  inconsist- 
ent. We  cease  wearing  aigrettes  because  the  collecting  of  them  often 
leaves  young  birds  to  die,  and  kill  every  mouse  and  mole  that  happens 
to  come  our  way,  though  their  young  must  die  as  do  those  of  the  birds. 
Some  of  us  wear  leather  shoes  while  arguing  for  a  vegetarian  diet  because 
animals  should  not  be  cruelly  slaughtered. 

Turning  to  the  second  and  third  ideas  stated  above,  we  note  that 
few  animals  which  feed  upon  a  variety  of  foods,  both  plant  and  animal, 
can  be  said  to  be  of  any  great  usefulness,  except  when  the  plants  eaten 
are  useless  to  man.  In  other  words,  the  good  done  the  farmer  by  an 
animal  which  eats  many  insects,  including  noxious  ones,  may  be  offset 
by  a  destruction  of  grain.  Birds  eat  a  variety  of  food.  Those  feeding 
upon  useful  plants  are  not  rated  as  of  great  economic  importance.  The 
bobolink,  for  example,  eats  grain  and  weed  seeds  in  the  spring  when 
insects  are  scarce;  soft-bodied  insects  in  June  and  July  when  seeds  are 
not  available.  In  August  the  insects  mature  and  are  hard  shelled.  The 
birds  now  reject  them  for  the  grain  seeds.  This  bird,  furthermore,  eats 
that  which  is  available  and  most  easily  secured  during  the  different 
seasons.  This  is  also  true  of  many,  probably  the  vast  majority  of 
animals.  The  food  of  fishes  is  to  a  considerable  extent  determined  by 
the  kind  of  food  available  where  they  are  living  (6).  Ruthven  (7)  has 
found  this  true  of  garter-snakes;  the  same  is  true  of  men. 

Many  animals,  birds  (8),  mammals,  reptiles  (9),  toads  (10),  and 
insects  destroy  quantities  of  noxious  insects,  but  along  with  them  many 
insects  that  are  enemies   and   parasites    of  the  noxious  ones  are  also 


lO  MAN  AND  ANIMALS 

destroyed.  The  parasites,  especially,  are  often  more  beneficial  to  man's 
interests  than  the  animals  which  devour  them,  and  which  take  good  and 
bad  without  the  slightest  discrimination  from  our  economic  point  of 
view.  Because  of  their  destruction  of  parasitic  insects  Severin  (8)  argues 
that  birds  should  not  be  protected.  Certain  mammals  and  reptiles  often 
show  a  decided  superiority  over  certain  birds  in  this  respect,  in  that  they 
are  strictly  predatory  and  are  not  directly  no.xious  at  any  time  of  year 
as  are  some  birds  which  feed  upon  grain. 

Many  animals  feed  extensively  upon  insect  pests  when  they  are 
numerous  and  accordingly  threaten  a  crop.  This  is  true  of  spiders, 
insects  (ii),  amphibians,  reptiles,  mammals,  and  birds  (8),  especially 
those  that  are  largely  predatory.  This  fact  is  the  only  sure  guaranty 
of  the  economic  value  of  many  birds,  and  is  perhaps  overworked  by  the 
fanciers  of  the  group.  This  value  belongs  equally  to  certain  insects, 
so  that  if  birds  were  not  devouring  such  insects  along  with  pests,  these 
hexapods  would  probably  be  able  to  put  the  pests  down.  The  other 
vertebrates  also  would  probably  be  able  to  put  down  the  pest  without 
the  aid  of  the  birds;  Forbes  has  said  that  a  balance  would  finally  be 
reached  if  all  the  vertebrates  were  exterminated  (see  26). 

In  the  preceding  pages  we  mention  "sanity  toward  nature." 
Sanity  toward  nature  is  based  upon  a  full  knowledge  of  available  facts. 
Partial  knowledge,  if  fully  depended  upon,  is  as  dangerous  as  falsehood, 
for  it  leads  to  false  interpretations.  We  must  know  nature,  not  a  part, 
but  the  whole,  if  we  wish  to  treat  the  simplest  everyday  problem  of 
our  relations  to  animals  intelligently  and  justly. 

Why  protect  birds  ?  Is  the  present  attempt  justified  ?  In  the 
answer  to  these  questions  all  sentimentalism  should  be  laid  aside.  It 
is  sometimes  urged  that  birds  have  a  greater  aesthetic  value  than  other 
animals.  This  it  seems  is  unjustified  unless  the  songs  of  some  constitute 
the  justification.  Persons  with  only  a  small  acquaintance  with  insects, 
mollusks,  fishes,  amphibians,  reptiles,  and  mammals  find  as  much  beauty 
in  these  groups  as  the  bird  fancier  does  in  his.  All  groups  should  be 
preserved  for  their  aesthetic  value  as  the  appreciation  of  it  depends 
entirely  upon  temperament,^  training,  and  especially  a  knowledge  of  the 

■  A  few  persons  known  to  the  writer  are  repelled  by  birds  because  of  their  claws, 
scaly  legs,  and  other  reptilian  characters.  Many  admirers  of  nature  and  animals  are 
not  attracted  by  birds  because  as  a  rule  they  must  be  seen  from  a  distance.  Inquiry 
at  close  range  necessitates  either  shooting  or  capturing  the  bird  and  neither  is  a  par- 
ticularly aesthetic  operation.  In  the  case  of  capture,  only  a  short  period  of  necessary 
neglect  usually  renders  the  surroundings  and  often  also  the  bird  not  only  not  aesthetic 


MAN  AND  NATURE  II 

group  in  question.  From  the  economic  viewpoint  there  is  not  a  complete 
agreement  as  to  bird  protection.  France  does  not  co-operate  with  Eng- 
land in  bird  protection  because  her  leaders  in  economic  thought  (Severin 
and  others)  have  ably  opposed  it  on  economic  grounds;  still  France  is 
more  progressive  than  England  in  agricultural  matters.  Other  things 
being  equal  there  are  but  two  more  reasons  for  special  measures  for  the 
preservation  of  birds  than  for  the  preservation  of  reptiles,  amphibians, 
or  insects.  First,  birds  are  subject  to  destruction  by  reckless  gunners. 
Second,  they  are  less  dependent  upon  natural  conditions  on  the  ground 
and  are  better  able  to  survive  after  land  has  been  put  under  cultivation 
than  some  other  groups.  Many  other  animals  whose  diets  are  varied 
have  been  exterminated  or  will  be  so  by  agriculture,  leaving  the  birds 
as  the  most  easy  point  for  protective  effort.  The  protection  of  birds 
should  not  be  urged  at  the  expense  of  the  extermination  of  other  animals 
because  of  their  alleged  occasional  attacks  upon  birds.  The  great 
danger  of  acting  on  partial  truth  regarding  animal  interdependences 
makes  societies  for  the  protection  of  birds  alone  scientifically  and  educa- 
tionally unjustified.  The  protection  of  all  groups  should  be  urged,  in 
particular  through  the  preservation  of  the  natural  features  upon  which 
they  depend.  It  is  well  to  protect  fishes  from  seiners  and  birds  from 
gunners  but  this  often  only  delays  their  fate.  We  must  also  consider 
where  they  will  breed  a  few  years  hence. 

When  one  comes  to  love  an  animal  or  a  group  of  animals,  he  is  in 
no  position  to  draw  scientific  conclusions  regarding  it.  For  this  reason 
bird  enthusiasts  are  not  always  to  be  trusted.  It  was  the  persistent 
efforts  of  such  "benefactors"  which  gave  us  that  detestable  avian  rat, 
the  English  sparrow,  the  feeding  or  sheltering  of  which  is  now  a  misde- 
meanor in  some  of  our  states. 

Should  we  slaughter  animals  ?  As  members  of  a  system  of  nature  in 
which  to  kill  is  the  first  law,  we  must  answer  in  the  affirmative.  Man  is 
the  master  of  all  destroyers.  Where  are  the  bison,  the  beaver,  the  elk, 
the  thousand  and  one  denizens  of  the  primeval  forest  and  prairie  ?  We 
scarcely  walk  over  a  path  or  lawn  without  bringing  "  death  "  and  "  suffer- 
ing" to  animals  of  some  sort.     The  crime  of  their  destruction  can  be  no 

but  malodorous  and  repulsive.  Thus  to  those  who  wish  to  examine  objects  closely 
other  animals  have  a  greater  aesthetic  value.  Claims  for  a  greater  aesthetic  value  for 
birds  must  be  based  upon  impressionistic  appreciation  of  them  in  connection  with 
landscape.  There  is  no  reason  to  desire  or  assume  that  this  interest  will  decrease 
with  time,  but  it  is  reasonable  to  suppose  that  with  further  dissemination  of  scientific 
ideas  and  methods  among  the  people  a  comparable  amount  of  more  serious  interest 
will  develop  in  connection  with  other  groups  and  perhaps  with  birds  as  well. 


12  MAN  AND  ANIMALS 

crime  at  all,  in  so  far  as  the  destruction  is  absolutely  unavoidable.  The 
wanton  and  useless  destruction  of  animals  not  condemned  as  noxious  by 
years  of  investigation,  though  probably  not  forbidden  by  the  example 
of  the  animal  world,  is  forbidden  by  the  best  sensibilities  of  every  civilized 
man  and  woman.  When  the  value  of  an  animal  to  us  is  in  question,  the 
animal  should  have  the  benefit  of  the  doubt,  and  we  should  hesitate 
long  before  introducing  animals  of  supposed  value.  Certainly,  also, 
every  animal  condemned  by  careful  investigators  should  be  destroyed 
whenever  opportunity  is  presented.  Mistaken  and  sentimental  ideas 
cause  the  killing  of  many  useful  animals  and  the  protection  of  many 
noxious  ones.  The  farmer  kills  snakes  and  skunks  whenever  he  has  the 
opportunity,  though  they  are  among  the  most  useful  animals.  Shrews 
are  master  destroyers  of  mice.  Still  many  people  mistake  shrews  for 
meadow  mice  and  destroy  them.  Likewise  the  housewife  kills  the 
house  centipede,  the  enemy  of  household  pests,  as  a  dangerous  and 
repulsive  creature  even  in  the  absence  of  any  knowledge  of  the  question- 
able charge  that  it  bites  young  infants.  Mistakes  are  not  confined  wholly 
to  uninitiated  individuals.  Misjudgment  by  the  officials  of  the  Brook- 
lyn Institute  of  Arts  and  Sciences,  possibly  influenced  by  the  sentiment 
of  Longfellow's  mistaken  poem  on  the  "Birds  of  Killingworth "  brought 
about  one  of  the  first  ofiicial  introductions  of  the  English  sparrow.  Thus 
we  see  that  the  complexity  of  the  problem  demands  careful  study  and 
conservative  action. 

2.      M.\N-MADE   COMMUNITIES 

Animal  communities  are  divisible  into  primeval  or  primary  com- 
munities, and  man-made,  or  secondary  communities  (12,  13).  As  has 
been  noted  when  civilized  man  enters  a  new  territory,  he  first  destroys 
all  large  game  which  threatens  himself  and  his  domestic  animals.  He 
then  destroys  the  natural  vegetation  and  other  animals  by  clearing  the 
timber,  burning  all  woody  debris,  and  plowing  and  putting  out  plants 
which  are  entirely  new  to  the  region.  Under  primeval  conditions, 
plants  are  arranged  irregularly,  as  roughly  indicated  by  the  letters  in 
Diagram  i ;  after  being  put  to  agricultural  purposes,  they  are  arranged  as 
in  Diagram  2.  The  plants  are  all  of  one  kind  and  are  arranged  in  rows. 
A  grove  of  the  original  vegetation  is  sometimes  left.  The  rate  at 
which  these  changes  take  place  is  directly  related  to  the  rate  at  which 
man  occupies  and  cultivates  the  new  territory.  As  compared  with 
natural  changes,  this  process  is  rapid  and  is  accompanied  by  an  equally 
rapid  decline  of  primeval  or  primary  communities. 


SECONDARY  COMMUNITIES 


13 


heddeb  hei  cd  efg  cbe  mi 
e  mefg  nm  be  de  fg  fgbn 
ghi  be  CO  dp  eqfr  gohifb 
bdcviwhxgyfzembndoc  e  ih 
efgxny  uinh  fgbhjnk  nsfg 
ghia  dftghtyb  hfj  tkibhc 
sdftunmgkiuoht  hyfgtrdcg 
dfgythufbnjks  vdg  fhtgry 
hfgt  fhgty  sdswaq  nfhjdl 
ghtyuwiokp  fbndhutbs  gtu 
vdfxzabjfmua  fgh  yfs  j  i 
edfgrthfinbghb  fgvnzxvcb 
erffghtjk  vbxzzasxscdfge 
thigjszxlkm,     j     hytfsdtrfb 

Diagram  i. — Showing  the  arrange- 
ment of  plants  and  animals  on  a  plot  of 
ground  under  primeval  conditions.  The 
letters  are  fortuitously  chosen  to  rep- 
resent the  fortuitous  arrangement  of 
plants  and  accordingly  the  animals  as- 
sociated with  them.  Thus  m,  n,  x,  and 
z  may  be  taken  to  represent  oak,  maple, 
basswood,  and  cherry,  respectively,  and 
the  animals  associated  with  each.  The 
other  letters  may  be  taken  to  represent 
herbs  and  shrubs  and  the  animals  asso- 
ciated with  them. 


edbeddgjcdbgdcgdcbedcdgebc 
f eceiej fad feed efadfcecdede 
cbaaaaaaaaaaaaaacb 
edaaaaaaaaaaaaaaed 
fg  aaaaaaaaaaaaaa  fg 
dcaaaaaaaaaaaaaadc 
eb  aaaaaaaaaaaaaa  eb 
dg  aaaaaaaaaaaaaa  dg 
fd  aaaaaaaaaaaaaa  fd 
dc  aaaaaaaaaaaaaa  dc 
fe  aaaaaaaaaaaaaa  fe 
eg  aaaaaaaaaaaaaa  eg 
fci  bedfg  beg  bdg  ded  jef  gdj  fc 
egj  ede  f  d  e  d  f  d  f  e  bf  eg 

Diagram  2. — Showing  the  arrange- 
ment under  agricultural  conditions. 
Here  the  plants  which  are  put  out  in 
rows  are  represented  by  a's  arranged  in 
rows.  There  are  certain  animals  asso- 
ciated with  such  plants  and  the  a's  rep- 
resent these  also.  Land  is  not  usually 
cultivated  close  to  the  fences  and  thus 
each  field  is  surrounded  by  a  border  of 
original  shrubs,  herbs,  and  sprouts  from 
the  original  trees.  These  and  the  ani- 
mals associated  with  them  are  still  for- 
tuitously arranged. 


3.      THE    DECLINE    OF    PRIMEVAL  COMMUNITIES   AT    THE    HEAD    OF 
LAKE   MICHIGAN 

By  Mabel  Brown  Shelford 
When  the  white  man  first  appeared  near  Chieago  no  secondary 
community  existed,  as  the  aborigines  lived  almost  entirely  by  hunting 
and  fishing.  They  cultivated  the  land  only  a  little,  and  are  accordingly 
to  be  ranked  with  the  larger  animals  as  a  part  of  the  original  communities. 
The  Indians  of  this  region  were  chiefly  Potawatomi,  although  there 
were  a  few  Chippewas  and  Ottawas  (14,  15).  Early  in  1833  (15)  about 
5,000  assembled  in  Chicago  to  treat  for  the  sale  of  their  entire  remaining 
possessions  in  Illinois  and  Wisconsin.  A  treaty  was  finally  ratified  and 
in  1835-36  (14,  15)  they  left  the  region  forever.  They  settled  in  Iowa 
for  a  time,  but  the  advancing  tide  of  civilization  drove  them 
farther  and  farther  west.  In  i8go  (16)  the  larger  part  of  the  Pota- 
watomi, about  950,  occupied  land  in  Kansas  and  Oklahoma.  The  region 
about  Chicago  was  particularly  adapted  to  the  life  of  the  Indians,  and 
it  was  probably  an  important  region  for  them,  as  well  as  their  successors. 
The  innumerable  water  courses  and  ponds  afforded  an  abundance  of 


14  MAN  AND  ANIMALS 

muskrats,  mussels,  fish,  etc.,  and  the  larger  game  of  the  land  was  par- 
ticularly abundant  and  diversified,  because  of  the  numerous  habitats 
represented.  Unfortunately,  a  fragmentary  record  is  all  we  have  of  the 
decline  of  the  primeval  communities  and  the  development  of  the  present 
ones.  These  records  apply  mainly  to  the  large  animals  of  Cook  County. 
The  time  of  the  disappearance  from  Southern  Michigan,  Northern 
Indiana,  and  Lake  County,  Illinois,  was  probably  much  later  and,  with 
the  exception  of  the  bison,  bear,  and  elk,  the  more  numerous  kinds  of 
game  nearly  all  still  occur  in  the  thinly  settled  portions  of  Illinois  (5a). 

The  earliest  explorers  of  this  region,  Marquette,  LaSalle,  and  others, 
speak  repeatedly  of  the  great  abundance  of  large  game  (17,  p.  34). 
LaSalle,  in  the  autumn  of  1679,  sailed  along  the  western  shore  of  Lake 
Michigan  until  the  end  of  the  lake  was  reached.  Landing,  he  found  deer, 
bear,  and  wild  turkeys  in  great  abundance.  Grapevines  loaded  with 
clusters  of  ripe  grapes  hung  from  the  tall  forest  trees  and  provided  a  rich 
feast  for  the  bears.  Continuing  toward  the  headwaters  of  the  Kankakee 
River,  one  stray  buffalo  was  found  sticking  in  a  marsh.  It  was  the 
beginning  of  winter  and  the  remainder  of  the  herd  had  probably  migrated 
South,  but  on  entering  the  headwaters  of  the  Illinois  River,  in  the  autumn 
of  the  following  year,  LaSalle  says  that  he  found  the  great  prairies 
"alive  with  buffalo"  (18). 

The  Indians  claimed  that  bison  were  very  plentiful  on  the  prairies 
until  the  Storm  Spirit,  becoming  angry  at  the  Indians,  sent  a  great 
snowfall  and  very  cold  weather,  which  drove  the  buffaloes  away  and 
they  never  returned  (19).  The  time  of  the  great  storm  seems  to  have 
been  between  1770  and  1780.  There  is  good  evidence,  however,  that 
they  were  found  in  considerable  numbers  in  this  part  of  the  state  as 
late  as  1800  (20).  Soon  after  this  they  entirely  disappeared.  As  late 
as  1838  traces  of  them  were  still  to  be  found  in  buffalo  paths,  well-beaten 
trails,  leading  generally  from  prairies  in  the  interior  of  the  state  to  margins 
of  large  rivers.  These  paths  were  very  narrow,  showing  that  the  animals 
went  in  single  file  (20), 

In  1800  and  for  many  years  afterward,  bears,  deer,  and  elk,  especially 
deer,  were  very  plentiful.  For  some  time  deer  continued  to  increase  with 
the  population  because  of  the  protection  found  in  the  neighborhood  of 
man  from  the  beasts  of  prey,  and  the  gradual  thinning-out  of  the  animals 
which  preyed  upon  them  (21).  Elk  had  almost  entirely  disappeared  in 
1837,  although  a  few  were  seen  occasionally  (22,  20,  20a,  23).  John 
Reynolds,  an  early  settler  of  Chicago,  tells  of  being  one  of  a  hunting 
party  that  wounded  an  elk  (20a).     In  1837  bears  were  seldom  seen  (20, 


SECONDARY  COMMUNITIES  1$ 

2oa).  Panthers  and  wildcats  were  found  occasionally  in  the  forests  (20a) . 
Beavers  and  otters,  once  numerous,  had  almost  gone  (20).  Among  the 
rodents,  the  varying  hare  disappeared  about  1834. 

In  1838  timber  wolves  and  coyotes  were  still  numerous  (200).  The 
deer  was  the  most  common  prey  of  the  timber  wolf,  but  these  failing,  they 
attacked  sheep,  pigs,  calves,  poultry,  and  even  young  colts  (20).  For 
some  time  the  increase  of  wolves  kept  pace  with  the  increase  of  live 
stock.  Reptiles  were  most  common  in  the  heavily  timbered  country. 
As  this  was  cleared,  they  disappeared,  while  the  prairie  reptiles  were 
destroyed  largely  by  prairie  fires. 

The  coyote  disappeared  about  1844,  while  the  timber  wolf  did  not 
entirely  disappear  until  about  ten  years  later  (22).  The  red  fox,  quite 
common  at  one  time  along  Lake  Michigan,  also  disappeared  from  this 
locality,  about  this  time,  although  still  found  occasionally  throughout 
the  state.  The  gray  fox,  once  quite  common,  was  no  longer  to  be  seen 
after  1854  (22).  The  black  bear  and  badger  had  entirely  disappeared  at 
the  same  date,  although  the  latter  was  still  common  farther  south  (22). 
The  fisher,  formerly  seen  frequently  in  the  heavy  timber  along  Lake 
Michigan,  was  no  longer  to  be  found.  The  mink,  skunk,  otter,  and 
weasel  were  still  common  (22). 

The  pocket  gopher  and  the  badger,  once  very  abundant,  were  very 
rare  in  1854  (22).  The  Canada  lynx  and  wildcat  were  still  abundant, 
but  of  the  panthers  a  single  individual  was  known  to  have  been  seen  in 
Cook  County  previous  to  1854(22).  The  decline  and  disappearance  of  the 
carnivores  was  followed  by  the  greatest  abundance  of  the  deer.  Accord- 
ing to  Wood  (21)  the  deer  began  to  disappear  from  Central  Illinois  about 
1865  and  had  totally  disappeared  in  1870.  Their  disappearance  from 
Cook  County  probably  antedated  this.  The  opossum,  at  one  time  not 
uncommon  in  this  vicinity,  was  now  rare  except  in  Southern  Illinois. 
The  only  trace  left  of  beavers  was  the  remains  of  their  dams  in  several 
streams  (22). 

4.      RECOGNIZABLE   SECONDARY  COMMUNITIES 

We  may  recognize  the  following  communities  in  the  order  of  their 
degree  of  difference  from  the  primeval  ones: 

a)  Communities  of  roadside,  fence-row,  and  abandoned  field  vegetation. 
— These  are  composed  chiefly  of  animals  which  commonly  inhabit  weeds 
and  thickets  along  the  edges  of  woods.  Since  these  are  most  nearly 
like  the  thicket  or  forest-margin  communities  treated  in  chap,  xiii, 
they  are  not  discussed  here. 


l6  MAN  AND  ANIMALS 

b)  Communities  of  parks  atid  pastures. — The  ground  and  subterranean 
animals  of  both  pastures  and  lawns  are  (near  Chicago)  chiefly  such 
prairie  animals  as  can  live  under  the  conditions  of  close  grazing  or  close 
mowing.  This  type  of  community  is  probably  better  developed  in 
the  pastures  than  in  the  parks  and  lawns.  The  thirteen-lined  squirrel, 
the  May  beetle  grub,  and  the  earthworms  are  among  the  common 
species.  On  the  lawns  a  few  grass-feeding  species  have  a  hazardous 
existence.  On  the  pasture  land  prairie  animals  are  more  abundant, 
and  an  occasional  prairie  bird  nests  in  a  clump  of  weeds  which  the  cattle 
have  not  eaten. 

Shrubs,  when  present,  are  inhabited  by  the  forest-margin  species. 
The  trees  present  are  inhabited  by  such  forest  animals  as  are  able 
to  live  without  the  characteristic  ground  conditions  of  a  forest  and 
under  the  more  severe  atmospheric  conditions.  There  are  various 
facts  pointing  to  a  difference  in  the  animals  attacking  trees  differently 
located  with  respect  to  other  trees;  for  example,  trees  standing  alone 
in  open  pastures  probably  have  a  very  different  fauna  from  trees  of 
the  same  species  growing  in  the  woods.  This  has  not  been  fully  investi- 
gated, however.  The  trees  of  the  parks  and  lawns  are  often  somewhat 
different  from  those  of  pastures,  because  of  the  introduction  of  many 
trees  not  native  to  the  region.  The  animal  communities  of  trees  fre- 
quently include  species  introduced  from  Europe. 

c)  Communities  of  lands  devoted  to  cultivated  annuals. — The  communi- 
ties of  farm  lands  are  made  up  of  animals  from  the  prairies,  the  forest 
margin,  and  marsh  vegetation,  together  with  introduced  species,  such  as 
the  cabbage  butterfly,  the  wheat  aphis,  the  Hessian  fly,  etc. 

d)  Communities  of  orchards. — The  communities  of  fruit-growing  lands 
are  made  up  of  the  animals  from  the  wild  haw,  wild  crab,  wild  plum,  and 
other  forest  trees,  the  greater  number  of  which  are  commonest  on  flood- 
plains.     There  are  also  a  number  of  introduced  species. 

e)  Communities  of  buildings. — The  communities  of  barns,  factories, 
and  dwellings  include  the  common  bedbug  (introduced),  the  silver  fish, 
the  cockroaches  (introduced),  various  buffalo  bugs  of  which  several  are 
introduced;  one  (Dermestes  lardarius  Linn.)  is  dangerous  to  stored 
materials  and  has  been  known  to  eat  holes  in  lead  pipe;  while  various 
spiders,  centipedes,  and  camel  crickets  occur.  The  house  mouse,  the 
Norway  rat,  and  the  English  sparrow  have  all  been  introduced.  About 
75  household  species  are  to  be  expected  in  and  about  Chicago, 

/)  Communities  of  polluted  waters. — In  connection  with  the  building 
of  cities,  we  always  find  the  introduction  of  sewage  and  industrial  wastes 


SECONDARY  COMMUNITIES  ly 

(24)  into  streams,  ponds,  and  lakes.  The  efifect  of  the  industrial  wastes 
differs  with  their  character.  Sewage  practically  destroys  all  the  life  of  a 
stream  or  lake  near  the  point  of  entrance,  through  the  introduction  of 
many  poisonous  substances,  through  the  increase  of  carbon  dioxide 
and  ammonia  and  through  the  lowering  of  oxygen  content.  Nichols  (25) 
states  that  the  oxygen  above  the  entrance  of  the  Paris  sewer  into  the 
Seine  was  g .  23  c.c.  per  liter,  and  immediately  below  i  .05  c.c.  per  liter,  a 
reduction  of  almost  90  per  cent.  The  typical  swift-water  fauna  of  Thorn 
Creek  at  Thornton  was  reduced  to  practically  nil  by  the  opening  of 
the  Chicago  Heights  sewage  system.  The  common  isopod  (Asellus  com- 
munis) was  the  only  animal  able  to  withstand  the  conditions.  At  a 
distance  from  a  point  of  entrance  of  sewage  the  amount  of  plankton 
is  increased  by  its  introduction  because  of  the  nitrogen  and  other  food 
for  plants  which  it  contains.  Forbes  (see  5a)  reports  that  the  amount 
of  plankton  near  Havana  in  the  Illinois  River  has  doubled  since  the 
opening  of  the  Drainage  Canal. 

5.      EQUILIBRIUM   IN   THE    SECONDARY   COMMUNITIES 

Equilibration  means  a  restoration  of  balance  in  the  numbers  of 
contending  organisms  of  the  community.  For  instance,  as  has  already 
been  noted,  the  deer  reached  their  maximum  number  with  the  correspond- 
ing destruction  of  the  carnivores  by  man.  This  indicated  that  the 
primeval  balance  between  the  carnivores  and  the  herbivores  had  been 
disturbed.  An  entirely  new  balance  has  now  been  established  through 
the  complete  destruction  of  both  the  large  hervibores  and  carnivores, 
by  man.  Most  of  our  knowledge  of  equilibration  in  communities  has 
resulted  from  the  study  of  the  secondary  communities  of  parks  and 
agricultural  lands.     Concerning  these  Forbes  (26,  p.  15)  has  said: 

There  is  a  general  consent  that  primeval  nature,  as  in  the  uninhabited  forest 
or  the  untilled  plain,  presents  a  settled  harmony  of  interaction  among  organic 
groups  which  is  in  strong  contrast  with  the  many  serious  maladjustrrients  of 
plants  and  animals  found  in  countries  occupied  by  man.  [All  our  serious  out- 
breaks of  insect  pests  are  instances  of  these  maladjustments.] 

To  man,  as  to  nature  at  large,  the  question  of  adjustment  is  of  vast  impor- 
tance, since  the  eminently  destructive  species  are  the  widely  oscillating  ones. 
Those  insects  which  are  well  adjusted  to  their  environments,  organic  and  inor- 
ganic, are  either  harmless  or  inflict  but  moderate  injury  (our  ordinary  crickets 
and  grasshoppers  are  examples) ;  while  those  that  are  imperfectly  adjusted, 
whose  numbers  are,  therefore,  subject  to  wide  fluctuations,  like  the  Colorado 
grasshopper,  the  chinch  bug,  and  the  army  worm,  are  the  enemies  which  we 
have  reason  to  dread.     Man  should  then  especially  address  his  efforts,  first, 


l8  MAX  AND  ANIMALS 

to  prevent  any  unnecessary  disturbance  of  the  settled  order  of  the  life  of  his 
region  which  will  convert  relatively  stationary  species  into  widely  oscillating 
ones;  second,  to  destroy  or  render  stationary  all  the  oscillating  species  injurious 
to  him ;  or,  failing  in  this,  to  restrict  their  oscillations  within  the  narrowest  limits 
possible.  For  example,  remembering  that  every  species  oscillates  to  some 
extent  and  is  held  to  relatively  constant  numbers  by  the  joint  action  of  several 
restraining  forces,  we  see  that  the  removal  or  weakening  of  any  check  or  barrier 
is  sufficient  to  widen  and  intensify  this  dangerous  oscillation,  and  may  even 
convert  a  perfectly  harmless  species  into  a  frightful  pest. 

Forbes  mentions  that  cottony  scale,  a  common  pest  in  our  parks, 
was  rare  in  natural  conditions.  The  close  setting  of  trees  has  favored 
its  increase.  Close  setting  is  nearly  always  a  factor  which  has  to  be 
considered. 

How  do  pests  arise?  The  recent  rise  of  the  wheat  aphis  may  be 
taken  as  an  example.  The  spring  of  1907  was  very  warm  in  the  southern 
part  of  the  wheat  belt,  and  the  grain  aphis,  which  is  said  to  reproduce 
freely  at  temperatures  from  100°  F.  to  below  freezing,  was  accordingly 
able  to  reproduce  without  interruption  from  its  parasites  and  enemies, 
which  do  not  become  active  at  such  low  temperatures  as  occurred. 
When  the  weather  grew  warmer  and  the  enemies  appeared  the  aphids 
were  so  numerous  that  the  work  of  the  enemies  was  hardly  appreciable. 
But  since  they  too,  like  the  aphids,  are  rapid  reproducers,  with  such 
favorable  conditions  they  were  able  to  increase  rapidly.  With  their  great 
increase  the  aphids  decreased  and  soon  their  numbers  were  far  too  great 
for  the  available  aphid  food.  The  enemies  therefore  decreased  because 
of  the  absence  of  sufficient  food,  and  this  portion  of  the  society  was 
accordingly  restored  to  an  approximate  equilibrium.  It  is  to  be  under- 
stood that  such  an  oscillation  in  the  society  is  far-reaching  in  its  effects. 
It  has  been  noted  that  such  oscillations  affect  the  whole  community. 
The  birds  and  mammals  find  certain  kinds  of  food  abundant  and  accord- 
ingly eat  things  different  from  what  they  do  under  different  conditions. 
Such  fluctuations  in  the  animal  communities  are  constantly  going  on. 

The  whole  process  may  be  summarized  as  follows : 

1.  Weather  conditions  unfavorable  to  enemies  and  favorable  to  plant  pest. 

2.  Increase  in  pest. 

3.  Increase  in  enemies. 

4.  Decrease  in  pest. 

5.  Decrease  in  enemies. 

6.  Balance. 


SECONDARY  COMMUNITIES  19 

6.      DISTRIBUTION   OF   SECONDARY   COMMUNITIES  ABOUT  CITIES 
AND  VILLAGES 

The  secondary  Communities  of  the  regions  about  Chicago  are  those 
typical  of  the  forest-border  area;  some  of  them  are  found  throughout 
the  temperate  world.  The  communities  in  and  about  cities  are  not 
particularly  different  from  those  discussed  in  general  terms  in  the  pre- 
ceding pages.  This  is  a  topic  for  special  study  and  we  can  give  but  the 
briefest  outline  here. 

When  a  city  is  in  the  village  stage  the  communities  of  barns  and 
dwellings  are  crowded  together  and  the  area  of  cultivated  land  and  park 
is  proportionally  larger  than  in  the  country.  As  a  village  grows  into  a 
city,  usually  a  central  area  of  business  houses,  factories,  and  cheap  tene- 
ments, dominated  by  the  communities  of  dwellings,  succeeds,  practically 
all  others  being  excluded.  This  type  usually  radiates  from  this  center 
for  a  short  distance  along  the  principal  lines  of  railroad  and  river  trans- 
portation. Except  for  these  narrow  radiations,  the  central  business 
section  is  surrounded  by  a  belt  of  residences,  which  are  of  the  park-lawn 
type,  usually  with  the  garden  or  cultivated  type  very  much  reduced 
or  entirely  eliminated.  This  type  extends  outward  along  all  lines  of 
passenger  transportation.  Toward  the  outskirts  of  this,  and  often 
quite  irregularly  arranged,  are  vacant  lots  and  squares  allowed  to  grow 
up  to  weeds  and  shrubs,  and  which  are  usually  occupied  by  forest- 
margin  animals.  Outside  of  and  adjoining  these  is  the  area  of  market 
gardening  on  the  lower  and  better  soils.  Other  tj^es  of  agricultural 
land  are  usually  poorly  cultivated  in  the  vicinity  of  cities. 

A  succession  of  conditions  dominated  by  one  or  another  of  the  second- 
ary communities  may  be  seen  as  the  pioneer  farm  passes  into  the  city 
stage.  The  pioneer-farm  type  is  succeeded  by  the  village  type,  with  its 
park-lawn  and  dwelling  combination.  The  village  gives  way  to  the 
business  center,  dominated  by  the  "dwelling"  animals.  As  these  pro- 
cesses take  place,  a  succession  of  the  various  grades  of  human  society  is 
noticeable.  In  dwellings  probably  the  first  resident  pest  is  the  clothes 
moth.  This  is  probably  succeeded  by  the  silver  fish  and  an  occasional 
cockroach  before  the  succession  of  the  various  grades  of  society  has 
begun.  Cracks  appear  in  the  woodwork  as  the  building  becomes 
"run  down,"  and  the  introduction  of  a  lower  grade  of  society  begins. 
The  bedbug  next  makes  its  appearance  and  marks  the  beginning  of  a 
rapid  lowering  of  standards  on  the  part  of  occupants.  The  house  mouse 
makes  its  appearance  and  is  followed  later  by  rats  and  vermin  which 
mark  the  final  stages  in  the  degeneration  into  a  cheap  tenement. 


20  MAN  AND  ANIMALS 

IV.    The  Economic  Importance  of  Animals 

Why  study  bugs  ?  Why  waste  your  time  upon  that  which  can  bring 
in  no  money?  Why  study  insects,  worms,  birds,  or  snakes?  These 
are  questions  which  are  often  asked  of  the  zoologist,  especially  such  as 
go  into  the  field  to  study  and  collect  animals  and  accordingly  meet  the 
public.  They  are  questions  which  the  zoologist  seldom  can  answer  to 
the  satisfaction  of  the  inquirer,  who  not  infrequently  thinks  the  observer, 
if  alone,  is  somewhat  insane.  Indeed,  the  conduct  of  one  Chicago 
entomologist  led  to  a  police  inquiry  into  his  sanity.  His  offense  was  that 
of  collecting  insects  under  an  electric  light.  The  questions  above  we 
shall  not  attempt  to  answer  here,  except  by  asking,  "Why  study  any- 
thing?" 

We  have  already  noted  the  complexity  of  the  problems  of  our  relation 
to  nature.  We  have  noted  the  disturbed  balance,  the  ravages  of  species 
introduced  by  accident  and  by  official  act.  We  have  noted  that  knowl- 
edge is  necessary  as  a  basis  for  "sanity  toward  nature."  We  have  still 
to  call  attention  to  some  of  the  economic  values  of  animals. 

It  follows  from  the  nature  of  the  animal  community  and  the  close 
interdependence  of  the  various  species  that  every  species  is  of  some 
importance  in  the  chain  of  food,  space,  and  other  relations,  and  every 
species  is  therefore  of  some  economic  importance.  A  few  are  of  great 
economic  importance.  In  addition  to  this  we  have  certain  definite 
practical  uses  and  well-known  matters  of  importance  attached  to  each  of 
the  animal  groups.  Taking  the  various  groups  in  their  taxonomic  order, 
we  note  the  following: 

The  protozoa  are  one  of  the  important  sources  of  food  of  larger  forms. 
Also  about  a  half-dozen  human  diseases  are  known  (27)  to  be  due  to  them, 
and  the  list  is  continually  growing.  The  shells  of  extinct  species  are 
an  important  part  of  chalk. 

The  uses  of  sponges  are  familiar.  Aside  from  their  importance  as 
food  of  other  forms,  the  coelenterates  furnish  us  with  corals  of  all  sorts. 
Among  the  echinoderms  the  starfish  is  an  important  enemy  of  the  oyster 
and  mussel  beds  (28).  The  ilatworms  are  important  as  parasites,  many 
species  having  been  recorded  in  the  body  of  man  (29).  The  round  worms 
are  of  considerable  importance  in  the  same  way,  and  some  are  serious 
enemies  of  grain.  The  earthworms  are  of  much  value  to  the  soil  (30). 
The  crustaceans  are  the  most  important  aquatic  invertebrates,  the 
Entomostraca  being,  from  the  standpoint  of  food  supply,  to  the  waters 
what  rooted  plants  are  on  the  land,  one  of  the  things  to  which  nearly  all 
food  interaction  can  be  traced.     Some  are  used  as  food  (lobsters,  shrimps, 


USEFUL  AND  NOXIOUS  ANIMALS  21 

crabs).  Some  are  quite  extensively  used  as  fertilizers  (horseshoe  crabs). 
The  mollusks,  aside  from  importance  to  other  animals,  give  us  our  pearls, 
pearl  buttons,  shell  work  of  all  kinds  (31),  fertilizers,  important  food,  ink, 
cuttlebone,  etc.  (32). 

The  insects  are  of  such  importance  that  nearly  every  state  and 
civilized  country  maintains  an  expensive  staff  of  trained  men  whose 
business  it  is  to  advise  the  public  in  regard  to  their  treatment  and  to 
investigate  the  relations  of  insects  to  industry.  Their  ravages  or  fear 
of  the  same  are  the  basis  of  some  of  the  speculation  which  enriches  some 
and  pauperizes  other  speculators  in  the  necessities  of  human  life.  Aside 
from  this  we  have  the  numerous  products  from  insects — tincture  of 
cantharides,  honey,  wax,  lac  {t,^),  carmine  (34),  and  cochineal.  Many 
are  used  as  human  food  in  the  tropics  (locusts,  water-bugs,  flies,  larvae 
of  the  palm  weevil,  etc.) .  Some  few,  such  as  the  scorpions,  are  poisonous. 
INIany  diseases  are  known  to  be  carried  from  person  to  person  by  insects 
and  arachnids  (cholera,  yellow  fever,  malaria,  sleeping  sickness,  typhoid, 
typhus,  bubonic  plague,  mountain  fever,  perhaps  leprosy)  as  well  as  a 
great  host  of  larger  parasites. 

We  turn  now  to  the  vertebrates,  which  are  familiar  and  their  uses 
quite  well  known.  From  this  group  we  get  our  leather,  furs,  animal 
oils  (snake  oil,  fish  oil,  turtle  oil,  lard,  whale  oil,  skunk  oil,  woodchuck 
oil,  neatsfoot  oil),  all  of  which  have  recognition  in  the  markets  and  some 
of  which  have  peculiar  properties  which  adapt  them  to  particular  pur- 
poses (32).  Glue,  gelatin,  bone  meal,  fertilizers,  bone  black,  etc.,  are 
extensively  used  in  industries;  meats,  dairy  products,  furs,  leather,  etc., 
are  necessities. 

We  must  not,  however,  fail  to  call  attention  to  animals  as  the  basis 
for  nearly  all  ex-perimental  study  of  life  processes,  of  heredity,  of  behavior 
and  psychology,  of  diseases  and  their  cure  and  prevention.  The  public 
should  disabuse  itself  of  the  idea  that  biological  investigators  are  wasting 
their  time  on  bugs,  for  lower  animals  are  the  only  material  upon  which 
the  problems  of  our  race  can  be  solved,  and  until  we  are  prepared  to  sub- 
mit ourselves  to  be  used  in  the  solution  of  our  own  problems,  biologists 
will  be  compelled  to  use  lower  animals  as  material. 


CHAPTER  II 

THE  ANIMAL  ORGANISM  AND  ITS  ENVIRONMENTAL  RELATIONS 
I.    Nature  of  Living  Substance 

The  bodies  of  living  plants  and  animals  are  made  up  of  living  matter 
known  as  protoplasm  (35,  chap.  ii).  Protoplasm  is  a  chemical  substance 
or  a  mixture  of  chemical  substances.  It  is  very  difficult  to  distinguish 
living  and  non-living  matter  by  definition.  However,  we  experience 
little  difficulty  in  separating  living  from  non-living  things.  This  is 
because  living  things  usually  possess  certain  definite  forms  and  ability  to 
reproduce  and  move  (especially  animals).  They  also  possess  irritability. 
This  is  the  property  by  virtue  of  which  the  force  applied  to  living  sub- 
stance is  not  in  proportion  to  the  force  resulting  (35,  p.  124).  One 
strikes  a  horse  with  a  whip ;  the  energy  which  the  horse  exerts  in  running 
is  not  proportional  to  the  force  of  the  blow,  but  is  far  greater. 

In  considering  the  environmental  relations  of  animals,  we  shall 
separate  our  discussion  into  that  concerned  with  form  and  that  con- 
cerned with  movement  (motor  activity)  and  other  functional  manifesta- 
tions. The  term  function  is  understood  to  cover  all  action  on  the  part 
of  the  various  parts  of  the  organisms,  motor  activity  included  (35a, 
chaps,  vii,  viii,  and  ix). 

II.    The  Relation  or  Form  or  Structure  to  Function 

The  term  animal  calls  forth  a  mental  picture  of  activity  and 
movement.  The  animals  with  which  we  are  most  familiar  are  those  of 
large  size,  such  as  fishes,  birds,  and  mammals.  They  and  the  groups 
to  which  they  belong  represent  only  a  very  small  part  of  the  animal 
kingdom,  but  we  may  consider  one  of  these  familiar  animals  as  an 
example  of  animals  in  general.     The  black  bass  will  serve  our  purpose. 

Such  a  fish  is  a  complicated,  highly  organized  animal  (36,  p.  183), 
possessing  many  organs,  such  as  fins,  gills,  teeth,  a  stomach,  an  intestine, 
a  liver,  a  heart,  and  a  brain  and  spinal  cord  harnessed  to  the  rest  of  the 
body  by  a  series  of  small  nerves  which  control  all  the  organs.  The  fins, 
which  are  the  external  organs  of  locomotion,  are  sufficient  in  number  to 
control  the  body  and  force  it  forward.  The  muscles  which  move  the 
fins  must  receive  nourishment  in  order  to  do  their  work.  The  nourish- 
ment is  carried  in  blood-vessels,  and  the  fluid  which  bears  the  nourish- 


STRUCTURE  AND  ENVIRONMENT  23 

ment  is  propelled  by  the  heart,  which  is  an  organ  possessing  definite 
form  and  a  certain  type  of  activity.  In  the  case  of  a  complex  animal 
like  the  black  bass,  we  might  elaborate  upon  the  relations  of  form  and 
structure  to  activity  and  function  almost  indefinitely.  It  is  obvious 
that  the  two  features  are  related  in  the  bass.  When  we  consider  animals 
which  possess  less  elaborate  structure,  the  relations  become  less  obvious 
upon  mere  inspection  because  organs  are  less  clearly  differentiated,  but 
they  are  still  more  easily  demonstrable  through  methods  employed  by 
the  biologist. 

In  both  the  lower  and  the  higher  organisms,  structure  may  be  con- 
trolled by  activity.  If  one  cuts  off  the  posterior  end  or  tail  of  a  flat- 
worm,  a  new  tail  is  formed.  Professor  Child  (37)  found  that  if  the 
animals  were  permitted  to  crawl  on  the  bottom  of  the  containing  vessels 
while  the  new  part  was  growing,  the  tail  was  pointed.  If  they  were  not 
allowed  to  crawl,  the  tail  was  rounded.  There  are  many  other  pieces 
of  experimental  work  which  show  that  structure  may  be  modified  by 
function.  In  but  few  cases,  however,  has  the  modified  structure  been 
found  to  be  inherited. 

At  present  the  relations  between  function  and  structure  have  not 
been  investigated  in  many  cases,  but  Child  has  made  their  relation 
quite  clear  by  comparing  the  organism  to  a  river.  "  The  relation  between 
structure  and  function  in  the  organism  is  similar  in  character  to  the 
relation  between  the  river  as  an  energetic  process  and  its  banks  and 
channel.  From  the  moment  that  the  river  began  to  flow  it  began  to 
produce  structural  configurations  in  its  environment,  the  products  of 
its  activity  accumulated  in  certain  places  and  modified  its  flow."  It 
deposits  and  removes,  and  thus  continually  "moulds  its  banks  and 
bottom,  forming  here  a  bar,  there  an  island,  here  a  bay,  there  a  point 
of  land,  but  still  flowing  on,  though  its  course,  its  speed,  its  depth,  the 
character  of  the  substances  which  it  carries  in  suspension  and  in  solution 
all  are  altered  by  the  structural  conditions  which  it  has  built  up  by  its 
own  past  activity"  (37a).  Thus  we  see  that  function  and  structure  are 
mutually  interactive  and  mutually  interrelated,  and,  for  the  sake  of 
clearness  only,  we  shall  separate  the  two  rather  sharply  in  our  discussion. 

Ill,    The  Basis  for  the  Organization  of  Ecology 

We  have  already  noted  that  ecology  deals  with  animal  life  as  lived  in 
nature,  or,  in  other  words,  with  the  relations  of  animals  to  their  environ- 
ments. The  question  of  what  aspects  of  these  relations  are  most  im- 
portant and  best  suited  as  a  basis  for  the  organization  of  ecology  at 


24  ENVIRONMENTAL  RELATIONS 

once  confronts  us.  The  selection  of  the  basis  for  organization  is  the  most 
important  step  before  us,  because  if  we  may  judge  from  the  history  of 
previous  attempts,  success  or  failure  depends  upon  this  selection.  It 
appears  from  the  preceding  pages  that  we  must  choose  between  emphasiz- 
ing structure  and  form  on  the  one  hand,  and  function  and  activity  on 
the  other. 

I.      FORM  AND   STRUCTURE   IN   RELATION   TO   ENVIRONMENT 

Each  article  of  furniture  in  the  room  where  I  am  sitting,  each  gar- 
ment which  I  am  wearing,  and  the  watch  in  my  pocket  were  made  for 
a  purpose,  and  are  adapted  to  the  purpose  for  which  the}^  were  made. 
This  is  so  generally  true  of  everything  with  which  we  have  to  do  in  our 
daily  lives  that  we  come  to  think  of  the  phenomena  of  nature  in  the  same 
terms,  often  without  stopping  to  consider  whether  or  not  it  can  be  true 
of  nature. 

The  reading  into  nature  of  the  idea  of  purpose  and  of  adaptation  has 
been  a  common  thing  since  the  earliest  !"ecords  of  science  (38,  pp.  52-56). 
Two  centuries  ago  the  idea  that  animals  were  created  to  fit  their 
particular  place  in  nature,  just  as  a  watch  is  made  for  a  purpose,  was  the 
idea  held  by  scientists;  indeed,  such  is  often  the  idea  of  non-scientific 
people  today.  Later,  Lamarck  conceived  the  idea  that  the  animal  was 
not  necessarily  adapted  to  a  given  place,  but  became  adapted  to  such  a 
place  by  trying  to  live  in  that  place,  or,  while  not  able  to  do  a  certain 
thing,  became  structurally  able  to  do  that  thing  by  trying  to  do  it,  just 
as  the  flatworm's  tail  becomes  pointed,  and  the  blacksmith's  arm  becomes 
strong  through  use.  Lamarck  (38,  p.  169;  39,  chap,  vi)  believed  that 
the  changes  brought  about  by  the  uses  which  the  organism  made  of  its 
parts  were  inherited,  but  science  has  found  chiefly  evidence  that  such 
changes  in  structure  are  not  inherited,  and  this  idea  of  the  origin  of 
adaptation  has  been  quite  generally  rejected. 

Following  Lamarck  came  Darwin,  who  conceived  the  idea  that  all 
the  individuals  of  a  species  which  came  into  existence  were  not  equally 
adapted  to  the  mode  of  life  that  was  necessary  for  them  and  those  best 
adapted  survived.  Their  characters,  being  born  with  the  individual, 
were  inheritable  and  the  adaptation  of  species  to  which  the  individuals 
belong  became  perfected  through  the  destruction  of  the  unadapted. 
The  destruction  of  the  poorly  adapted  and  the  survival  of  the  best 
adapted  is  called  "natural  selection"  or  the  "survival  of  the  fittest." 

Following  Darwin,  a  large  number  of  investigators  set  to  work  to 
apply  his  theory  to  the  phenomena  of  nature  in  detail.     The  ideas  of 


STRUCTURE  AND  ENVIRONMENT  25 

"protective  resemblance,"  "mimicry,"  and  "warning  coloration"  were 
developed  (40).  The  idea  of  protective  resemblance  is  as  follows:  A 
certain  insect  is  green  and  lives  on  green  leaves.  The  natural-selection 
observer  at  once  theorizes  to  the  effect  that  the  animal  is  green  because, 
at  a  time  when  not  all  the  individuals  of  that  species  were  green,  the 
birds  secured  all  those  not  green  and  left  the  green  ones  because  they 
were  difficult  to  see;  now  therefore  only  green  ones  occur.  In  the  case 
of  mimicry,  one  species  of  insect  (or  other  animal)  resembles  another. 
The  theorist  finds  or  thinks  that  one  of  them  is  distasteful  to  birds  and 
other  animals.  He  further  discovers  or  concludes  that  the  species  not 
having  a  bad  odor  or  taste  is  not  eaten  by  enemies  because  it  resembles 
the  distasteful  species.  The  species  having  the  bad  odor  or  taste  is  the 
model.  The  species  not  having  the  bad  odor  or  taste  is  the  mimic. 
The  mimic  arose  and  attained  its  perfection  because  those  individuals  of 
the  mimic  species  which  resembled  the  model  species  survived. 

In  the  case  of  warning  coloration,  the  animal  supposed  to  be  dis- 
tasteful has  bright  colors.  The  birds,  learning  that  certain  bright 
colors  are  associated  with  bad  tastes,  avoid  such  strikingly  colored  forms. 
Accordingly,  the  most  brilliantly  colored  distasteful  forms  survive. 

More  detailed  study  in  recent  years  has  tended  to  show  such  specula- 
tions to  be  of  questionable  value.  Such  ideas  must  remain  matters  of 
speculation  at  present,  because  of  the  difficulty  of  applying  experimental 
methods  to  their  study.  Based  on  a  theory  with  few  facts  to  support  it, 
and  not  withstanding  critical  analysis,  the  ideas  of  structural  adaptation, 
including  any  of  the  ideas  just  mentioned,  are  not  a  good  basis  for  the 
organization  of  a  science  of  ecology. 

The  revival  of  an  old  idea  that  animal  species  arose  in  places  and 
by  methods  unknown,  and  by  chance  found  places  to  which  they  were 
adapted,  now  constitutes  the  central  idea  of  the  most  recent  theory  of 
the  origin  of  adaptation  and  is  to  be  favored  as  a  working  hypothesis, 
because  it  may  be  tested  experimentally  (41). 

Another  reason  for  the  inadvisability  of  attempting  to  organize 
ecology  on  the  basis  of  structure  lies  in  the  fact  that  structural  changes 
resulting  from  stimulation  by  the  environment  are  rarely  of  advantage 
or  disadvantage  to  the  animal,  and  further  that  the  structure  of  motile 
animals  is  not  readily  modified  by  the  environment.  A  considerable 
number  of  animals  are  larger  or  smaller,  lighter  or  darker,  according 
to  conditions  surrounding  them  during  development  (42),  but  few 
biologists  see  any  advantage  or  disadvantage  to  the  animal  in  these 
changes. 


26  ENVIRONMENTAL  RELATIONS 

2.      FUNCTION   AND   ACTIVITIES   IN   RELATION   TO   ENVIRONMENT 

We  have  just  noted  that  from  the  point  of  view  of  structural  adapta- 
tion, structure  cannot  be  separated  from  function.  It  is  equally  true 
that  from  the  point  of  view  of  physiology,  function  and  behavior  cannot 
be  separated  from  structure. 

Turning  again  to  the  black  bass,  which  we  have  already  used  to 
illustrate  some  points,  we  note  that  for  the  simple  act  of  swimming,  the 
digestive  tract,  gills,  heart,  blood-vessels,  brain,  and  muscles  are  neces- 
sary'. They  must  all  be  present  to  furnish  the  animal  with  the  necessary 
energy  and  impulses  to  make  motions  for  swimming.  It  is  obvious  that 
there  is  a  division  of  labor  between  the  different  organs,  and  if  any  of 
them  are  impaired  or  injured,  or  interfered  with,  the  work  cannot  go  on 
in  its  proper  manner,  or  perhaps  not  at  all.  The  organism  is  a  complex 
of  correlated  parts  and  processes.  If  we  interfere  with  any  of  these,  e.g., 
the  circulation  of  the  blood  of  the  fish,  which  might  be  done  in  many 
ways,  the  whole  system  of  interdependent  processes  is  interfered  with. 
The  fish  is  a  highly  organized  animal,  but  the  same  general  laws  of 
relations  of  processes,  such  as  respiration,  circulation  of  food  materials, 
digestion,  etc.,  apply  to  animals  in  which  there  are  no  special  or  definite 
organs  to  take  care  of  each  separate  process.  The  interdependence  of 
processes  in  the  organism  is  sometimes  called  physiological  proportionality 
(37a),  i.e.,  the  work  accomplished  by  any  one  set  of  organs  or  processes 
is  proportional  to  that  of  another  set  or  all  the  sets  of  processes  in  the 
organism.  When  the  processes  are  going  on  in  perfect  accord  and  in 
proper  proportionality,  the  organism  is  said  to  be  in  physiological  equilib- 
rium. The  conception  of  the  organism  stated  above  may  best  be  used 
in  considering  the  relations  of  animal  activities  and  functions  to  the 
environment. 

It  is  generally  held  that  the  various  animal  forms  are  made  up  of 
different  kinds  of  protoplasm  and  that  the  eggs  of  no  two  species  are 
alike  as  to  protoplasmic  character.  They  may  differ  only  slightly  in 
appearance,  as  for  example  the  eggs  of  a  frog  and  of  a  salamander,  but 
even  if  the  eggs  of  these  two  animals  are  laid  in  the  same  pool  at  the 
same  time,  and  the  conditions  are  essentially  the  same  surrounding  the 
two  masses,  one  mass  of  eggs  develops  into  frogs  and  the  other  into 
salamanders  (43,  p.  8).  The  only  logical  conclusion  is  that  the  composi- 
tion or  protoplasm  of  the  eggs  is  different. 

It  must  be  noted  at  the  outset,  therefore,  that  different  organisms  are 
made  up  of  different  kinds  of  protoplasm;  furthermore,  combinations  of 


ACTIVITY  AND  ENVIRONMENT  27 

the  same  living  substances  into  different  special  organs  would  of  necessity 
give  different  organisms  different  properties. 

Different  chemical  substances  often  behave  differently  under  a  given 
condition  of  temperature,  pressure,  or  light,  etc.  Likewise,  if  a  cockroach 
and  a  house  fly  are  liberated  in  the  center  of  a  room,  the  fly  goes  to  a 
window  and  the  cockroach  into  a  shadow;  furthermore,  a  cold  night  will 
kill  the  house  fly,  while  to  dispose  of  the  cockroach  the  proverbial  two 
wooden  blocks  are  necessary.  Both  differences  in  physiological  char- 
acter (behavior)  are  due  to  differences  in  the  organisms.  Different 
organisms  often  behave  differently  in  the  same  intensity  of  the  same 
physical  factor,  for  example,  the  same  temperature  or  light,  just  as  the 
different  chemical  substances  do.  Different  chemical  substances  often 
undergo  different  changes  with  variations  in  temperature,  pressure,  or 
light.  Each  has  its  characteristic  reactions.  Still  whole  groups  may  be- 
have quite  similarly.  Changes  in  conditions  affect  organisms.  We  have 
all  noted  the  effect  of  a  cool  day  upon  the  activity  of  animals  such  as  the 
insects.  Different  organisms  usually  behave  differently  in  some  respects, 
while  whole  communities  may  behave  quite  similarly  in  other  respects. 

a)  The  organism  as  unaffected  by  the  environment. — When  all  of  the 
external  conditions  continue  approximately  the  same,  the  activities  of 
the  organism  are  called  spontaneous  (35,  p.  347).  As  has  been  stated, 
the  organism  is  naturally  active.  Accordingly,  movements  may  possibly 
take  place  as  a  manifestation  of  the  released  energy  inside  the  animal, 
or  of  disturbances  and  changes  in  the  organism  which  are  not  directly 
initiated  by  the  environment.  Probably  animals  often  move  without 
any  external  stimulation  (44,  chap.  xvi).  One  who  has  observed  the 
wonderful  Japanese  dancing  mice  knows  that  their  constant  movement 
may  not  be  the  result  of  the  external  conditions,  but  of  the  energy  which 
is  expended  within  the  organism. 

Jennings  (44)  stated  that  these  spontaneous  movements  must  be 
recognized  in  the  study  of  behavior,  and  that  many  errors  have  arisen 
from  their  neglect.  If  we  see  an  animal  moving,  we  should  not  assume 
that  it  is  moving  because  of  some  external  condition  acting  on  it  at  the 
time.  It  may  be  due  to  previous  stimulation  or  it  may  be  the  result 
of  internal  conditions.  Growth,  maturity,  reproduction,  and  death  are 
accompanied  by  changes  in  behavior,  structure,  etc.  All  may  take  place 
without  great  change  in  environment. 

b)  The  organism  as  affected  by  the  environment. — Many  organisms  are 
not  sensitive  to  slight  changes  in  the  external  environment.     Having 


28  ENVIRONMENTAL  RELATIONS 

developed  in,  and  never  having  been  separated  from,  fluctuating  con- 
ditions, they  do  not  respond  to  all  environmental  fluctuations.  The 
terms  approximately  constant  and  spontaneous  used  above  are  then 
both  relative.  Any  change  in  the  external  conditions  sufficient  to  alter 
the  internal  processes  of  the  organism  is  called  a  stimulus.  The  \-isible 
movement  of  the  organism  or  other  phenomena  resulting  from  stimulation 
is  called  the  reaction.  The  reaction  may  be:  (o)  cessation  of  movement, 
(6)  initiation  of  movement,  or  (c)  change  in  kind  or  direction  of 
movement. 

Fluctuations  in  the  environmental  conditions  in  nature  usually 
involve  more  than  one  factor.  Experiments  are  necessary  to  determine 
which  factor  is  affecting  the  activities  of  the  animal.  The  effect  of  the 
various  factors  taken  singly  upon  a  few  animals  has  been  determined. 
These  factors  are  pressure,  including  currents  and  contact  with  other 
bodies,  shock,  vibrations  and  sound,  temperature,  water,  chemicals,  light, 
etc.  For  example,  if  we  lower  the  temperature  surrounding  an  insect 
sufficiently,  it  will  become  apparently  stiff  and  lifeless  (35,  p.  396).  If  the 
temperature  is  raised  again,  the  animal  becomes  active.  The  activity  is 
increased  as  the  temperature  is  raised  until  a  degree  of  heat  nearly  high 
enough  to  kill  it  is  reached,  when  the  animal  becomes  inactive  again.  If 
the  temperature  is  raised  only  a  little  more,  the  animal  dies.  In  general 
changes  in  any  factor  produce  either  excitation  or  depression,  or  in 
other  words,  an  acceleration  or  retardation  of  the  activities.  In  con- 
nection with  the  acceleration  or  retardation  of  activity,  animals  fre- 
quently turn  toward  or  away  from  the  source  of  light  or  sound,  or  in  the 
direction  of  a  current  of  air  or  water.  Or  they  congregate  at  a  point 
where  the  temperature  or  the  light  or  the  chemical  conditions  interfere 
least  with  their  internal  processes. 

Such  turnings  or  congregations  are  called  tropisms'or  taxes  (45).  If 
the  animals  turn  toward  or  go  toward  the  source  of  stimulation  they  are 
said  to  be  positive.  If  they  turn  away  or  go  away  or  congregate  at  a 
distance  they  are  called  negative.  The  names  applied  to  the  reactions 
are  given  below.  There  are  various  theories  as  to  the  exact  manner  in 
which  these  turnings  and  congregations  are  brought  about,  but,  as  a 
rule,  animals  congregate  where  their  internal  processes  are  least  inter- 
fered with,  and  random  movements  nearly  always  play  some  part  in 
the  process.  There  are  two  sets  of  terms  applied  to  such  responses 
as  described  above;  they  are  given  in  parallel  columns  below  (p.  29). 
Taxis  means  arrangement.     Tropism  means  turning. 


ACTIVITY  AND   ENVIRONMENT 


29 


Reactions  to  light  are  called 

"  temperature  are  called 

"  .         moisture  are  called 

"  gravitation  are  called 

"  chemicals  are  called 

"  contact  are  called 

"  pressure  are  called 

"  electric  currents 

"  current  in  medium 


phototaxis      or  heliotropism 


thermotaxis  "  thermotropism 

hydrotaxis  "  hydrotropism 

geotaxis  "  geotropism 

chemotaxis  "  chemotropism 

thigmotaxis  "  stereotropism 

barotaxis  "  barotropism 

galvanotaxis  "  galvanotropism 

rheotaxis  "  rheotropism 

If  we  place  a  number  of  common  pond  snails  in  a  dish  which  is  dark 
at  one  end  and  grades  to  sunlight  at  the  other,  we  find  that  most  of  the 
snails  are  found  after  a  time  in  faint  light.  The  explanation  of  this 
phenomenon  is  that  the  snails  are  stimulated  by  intense  light  and  by 
very  weak  light,  i.e.,  either  of  these  conditions  of  illumination  interferes 
with  some  of  the  internal  processes  of  the  animal,  and  the  random 
movements  which  result  bring  the  animal  into  various  conditions,  one  of 
which  (faint  light)  relieves  the  disturbance.  The  animal  then  ceases  to 
move  at  random,  because  its  internal  processes  are  no  longer  interfered 
with  by  the  stimulus.  The  snail's  activity  is  lessened,  or  it  turns  back 
from  regions  of  either  too  strong  or  too  weak  light;  accordingly,  most  of 
the  snails  are  found  in  faint  light.  The  internal  processes  have  been 
adjusted  or  regulated.  The  snails  are  said  to  be  negatively  phototactic  to 
strong  light  and  positively  phototactic  to  weak  light. 

The  animal  lives  in  an  environment  which  is  constantly  changing. 
Its  spontaneous  movements  are  constantly  bringing  it  into  different 
conditions.  It  tends  to  regulate  its  internal  processes  by  selecting  the 
I  point  in  the  environment  in  which  its  internal  processes  are  not  dis- 
turbed. The  writer  has  observed  snails  in  ponds.  They  move  into  their 
optimum  light,  i.e.,  the  light  which  does  not  disturb  them.  On  dark 
days  they  are  found  in  the  light.  On  sunny  days  they  are  found  in  the 
shade  of  the  vegetation.  They  shift  their  position  according  to  condi- 
tions and  their  distribution  at  any  given  time  is  a  better  index  of 
conditions  than  the  distribution  of  plants  in  the  same  pond. 

c)  Modifiability  of  behavior  and  different  physiological  states. — We  all 
know  that  our  actions  may  be  modified  by  experience.  There  are  but 
few  people  who  have  not  been  greatly  frightened  by  some  accident 
accompanied  by  a  characteristic  noise.  For  days  afterward,  one  starts 
at  the  slightest  unexpected  noise.  His  response  has  been  modified. 
It  is  a  well-known  fact  in  animal  training  that  an  animal  may  be 
"spoiled,"     A  horse  may  be  ruined  for  some  purposes  by  an  accident 


30  ENVIRONMENTAL  RELATIONS 

which  has  caused  it  to  run  away,  for  it  thereby  acquires  the  habit  of 
running  away.  In  the  lower  animals  we  find  the  same  condition;  their 
behavior  may  be  modified,  but  the  modifications  are  less  permanent 
than  in  man  and  other  mammals. 

Changes  within  the  organism  cause  approximately  fixed  environ- 
mental conditions  to  act  as  stimuli.  Changes  are  going  on  all  the  time 
within  the  organism.  Such  changes  may  result  from  growth,  maturation 
of  sexual  products,  or  other  causes.  The  organism  may  be  in  physiologi- 
cal equilibrium  (see  p.  26)  in  a  given  set  of  conditions  before  the  devel- 
opment of  the  eggs  and  spermatozoa  begins,  but  these  processes  are 
accompanied  by  other  great  physiological  changes,  which  frequently  put 
the  animal  out  of  adjustment  to  its  surroundings. 

The  queen  ant  is  in  physiological  equilibrium  in  the  darkness  of  the 
nest  until  she  becomes  sexually  mature.  She  then  becomes  positively 
phototactic,  goes  toward  the  light,  flies  from  the  nest  with  the  males, 
and,  being  negatively  geotactic,  stays  away  from  the  ground.  When  fer- 
tilized, she  at  once  becomes  negatively  phototactic,  positively  geotactic, 
and  positively  thigmotactic.  Accordingly  she  places  her  body  in  contact 
with  the  ground,  and  burrows  into  it  and  starts  a  new  colony.  The  ant 
is  then  in  a  different  physiological  state  after  becoming  sexually  mature, 
and  in  a  third  state  after  fertilization. 

3.      ENVIRONMENTAL  CHANGES 

a)  Daily  changes. — The  physiological  responses  of  animals  to  these 
changes  have  an  important  bearing  on  their  relation  to  each  other. 
Some  forms  are  diurnal,  others  nocturnal,  others  crepuscular.  Some  are 
probably  active  all  the  time,  but  move  into  different  positions  in  the  day 
and  in  the  night.  For  example,  some  pelagic  animals  (which  float  or 
swim  freely  in  water  and  are  independent  of  bottom)  are  numerous  near 
the  surface  at  night,  but  migrate  to  considerable  depths  during  the  day, 
as  a  response  to  light.  Many  animals  bear  relations  to  day  and  night, 
which  in  some  cases  may  be  of  an  adaptive  character.  Some  forms  are 
active  during  the  day,  and  hide  themselves  during  the  night,  either  in 
burrows  or  under  suitable  objects.  Those  which  simply  crawl  under 
loose  objects  during  the  day  frequently  appear  at  artificial  lights  in 
the  evening. 

It  is  not  impossible  that  there  are  structures  in  the  bodies  of  many 
animals  which  are  the  product  of  the  different  conditions  of  day  and  night 
during  critical  periods  of  growth.  Thus  Riddle  (46)  has  found  that  the 
barrings  of  the  feathers  of  certain  birds  are  due  to  low  blood  pressure  at 
night  (feeble  circulation)  during  the  growth  of  the  feathers. 


HABITAT  PREFERENCE  31 

b)  Seasonal  changes. — These  involve  great  changes  in  the  physio- 
logical states.  Inacti\'ity  is  the  rule  in  winter;  growth  and  activity  in 
the  other  seasons.  The  plants  and  animals  of  a  locality  do  not  all  reach 
sexual  maturity  or  the  greatest  growth  activity  at  the  same  time  during 
the  growing  season,  but  different  species  succeed  each  other  as  the  season 
advances  (47).  The  food  and  enemies  of  a  given  species,  which  is  present 
in  an  animal  community  for  a  large  part  of  the  growing  season,  differ 
from  time  to  time. 

c)  Weather  changes. — These  constitute  fluctuations  of  conditions 
calling  forth  special  types  of  behavior.  Some  animals  hide  when  the 
wind  begins  to  blow;  some  burrow  into  the  ground  on  cool  and  cloudy 
days. 

4.      HABITAT  PREFERENCES 

By  virtue  of  being  unlike  or  possessing  different  properties,  the  various 
animal  species  require  different  conditions  for  the  best  adjustment 
of  their  internal  processes.  For  example,  the  carp  lives  in  shallow  and 
muddy  ponds  and  rivers,  while  the  brook  trout  lives  only  in  clear  swift 
streams.  These  two  organisms  are  able  to  move  about  and  find  places 
to  which  they  are  suited.  The  differences  between  them  are  clearly 
indicated  by  the  differences  in  the  habitats  which  they  prefer. 

By  observation  and  by  experimentation  it  has  been  shown  that 
animals  select  their  habitats.  By  this  we  do  not  mean  that  the  animal 
reasons,  but  that  selection  results  from  regulatory  behavior  (p.  29). 
The  animal  usually  tries  a  number  of  situations  as  a  result  of  random 
movements,  and  stays  in  the  set  of  conditions  in  which  its  physiological 
processes  are  least  interfered  with.  This  process  is  called  selection  by 
ttial  and  error.  If  animals  are  placed  in  situations  where  a  number  of 
conditions  are  equally  available,  they  will  almost  always  be  found  living 
in  or  staying  most  of  the  time  in  one  of  the  places.  The  only  reason  to 
be  assigned  for  this  unequal  or  local  distribution  of  the  animals  is  that 
they  are  not  in  physiological  equilibrium  in  all  the  places.  However, 
some  animals  move  about  so  much  that  it  is  with  some  difficulty  that  we 
determine  what  their  true  habitats  are. 

5.      THE   MOST   IMPORTANT   ACTIVITIES    OF   ANIMALS 

Animal  activities  are  classified  as  feeding,  breeding,  hiding,  sleeping, 
etc.  The  strength  of  a  chain  is  the  strength  of  its  weakest  link;  the 
activity  which  determines  the  range  of  conditions  under  which  a  species 
will  be  successful  is  the  activity  which  takes  place  within  the  narrowest 
limits.     This  is  usually  the  breeding  activity.     The  breeding  instincts 


32  ENVIRONMENTAL  RELATIONS 

are  the  center  about  which  all  other  activities  of  the  organism  rotate, 
and  the  breeding-place  is  the  axis  of  the  environmental  relations  of  the 
organism  (6,  48,  49,  50).  Migratory  birds  are  our  most  striking  motile 
forms.  They  may  migrate  great  distances,  but  always  come  back  to  the 
same  kind  of  area  to  breed. 

Failure  to  recognize  the  relative  importance  of  the  different  activities 
is  in  part  responsible  for  the  general  unorganized  state  of  our  knowledge 
of  natural  history.  Investigators  have  often  failed  to  interpret  the 
relations  of  animals  to  their  environments  because  they  have  regarded 
the  records  of  the  occurrence  of  all  stages  of  the  life  history  as  equally 
important.  They  have  considered  the  occurrence  of  the  most  motile 
stage  in  the  life  history  as  significant,  for  example  the  occurrence  of  an 
adult  butterfly.  Plant  ecologists  would  have  met  with  equal  success  if 
they  had  studied  only  the  environmental  relations  and  distribution  of 
wind-disseminated  seeds. 

We  have  noted  reasons  for  not  putting  primary  emphasis  on  structure 
and  form  as  a  basis  for  the  organization  of  ecology.  The  above  discus- 
sion shows  that  activities  are  actually  most  important,  and  accordingly 
may  be  used  in  ecological  study.  However,  since  structure  and  activity 
(function)  are  always  correlated,  we  should  never  lose  sight  of  the  former. 

IV.    Scope  and  Meaning  of  Ecology 

I.      SPECIES   AND  ECOLOGY 

In  practice,  species  are  diagnosed  in  terms  of  structures,  such  as 
number  and  arrangement  of  bristles,  hair,  form,  color,  size,  etc.  Such 
characters  are  commonly  called  morphological.  In  ecology,  the  morpho- 
logical characters  of  species  are  of  little  or  no  significance.  Still,  since 
habitat  preferences  are  commonly  closely  correlated  with  the  characters 
used  to  separate  species,  some  progress  in  ecology  can  be  made  by  the 
study  of  the  distribution  and  environmental  relations  of  species,  but  if 
this  is  not  carefully  checked  by  experimentation  one  may  constantly 
fall  into  error. 

2.      MORES — PHYSIOLOGY   THE   BASIS   OF   ECOLOGY 

As  we  have  already  seen,  ecology'  is  that  branch  of  general  physiology 
which  deals  with  the  organism  as  a  whole,  with  its  general  life  processes  as 

'  The  unorganized  phases  of  ecology  are  sometimes  called  natural  history,  biology, 
ethology,  or  bionomics,  but  usually  by  men  having  little  understanding  of  plant  ecology 
or  who  for  some  reason  object  to  the  word  ecology  (see  35a,  pp.  18-21).  The  term 
ecology  is  applied  to  those  phases  of  natural  history  and  physiology  which  are  organ- 
ized or  are  organizable  into  a  science,  but  does  not  include  all  the  unorganizable  data 


PHYSIOLOGY  AND  ECOLOGY  t,t, 

distinguished  from  the  more  special  physiology  of  organs  (13,51).  With 
these  limitations  upon  the  term  physiology,  what  may  be  termed 
physiological  life  histories  (52)  covers  much  of  the  field.  Under  this 
head  fall  matters  of  rate  of  metabolism,  latency  of  eggs,  time  and  condi- 
tion of  reproduction,  necessary  conditions  for  existence,  and  especially 
behavior  in  relation  to  the  conditions  of  existence.  Reactions  of  the 
animal  maintain  it  in  its  normal  environment;  reactions  are  dependent 
upon  rate  of  metabolism  (53  and  citations),  which  may  be  modified  by 
external  conditions.  Behavior  reactions  throughout  the  life  cycle  are  a 
good  index  of  a  physiological  life  history. 

If  we  knew  the  physiological  life  histories  of  a  majority  of  animals, 
most  other  ecological  problems  would  be  easy  of  solution.  The  chief 
difficulty  in  ecological  work  is  our  lack  of  knowledge  of  physiological  life 
histories.  With  elaborate  facilities  these  may  be  worked  out  in  a 
laboratory.  Ecology,  however,  considers  physiological  life  histories 
primarily  in  nature,  and  for  this  reason  the  central  probleYn  of  ecology 
is  the  mores  (13)  problem.  This  may  be  defined  as  the  problem  of 
physiological  life  histories  in  relation  to  natural  environments  together 
with  that  of  the  relations  of  organisms  in  communities.  The  latter  is 
not  a  part  of  physiological  life  histories,  the  mores  conception  being  the 
broader.  An  ecological  classification  is  a  classification  upon  a  physio- 
logical basis,  but  since  structure  and  physiology  are  inseparable,  we 
must  not  forget  the  relations  of  structure  to  ecology  and  to  ecological 
classification.^ 

V.     Communities  and  Biota 

I.      BASIS 

Animals  select  their  habitats  probably  by  trial  and  error.  The  simple 
fact  of   selection  is,  we  believe,  familiar  to  all  naturalists.     A  given 

of  natural  historj'.  There  has  never  been  any  attempt  to  organize  natural  history 
and  physiological  data  into  a  science  under  the  head  of  ethology,  biology,  or  bio- 
nomics, and  the  use  of  these  terms  will  not  seem  justified  until  the  materials  to  which 
they  have  been  applied  are  organized  into  a  science. 

'  Mores  (Latin  singular  vios),  "behavior,"  "habits,"  "customs";  admissible  here 
because  behavior  is  a  good  index  of  physiological  conditions  and  constitutes  the 
dominant  phenomenon  of  a  physiological  life  history  and  of  community  relations. 
We  have  used  this  term  just  as  form  and  forms  are  used  in  biology,  in  one  sense  to 
apply  to  the  general  ecological  attributes  of  motile  organisms;  in  another  sense  to 
animals  or  groups  of  animals  possessing  particular  ecological  attributes.  When  apphed 
in  this  latter  sense  to  single  animals  or  a  single  group  of  animals  the  plural  is  used  in 
a  singular  construction.  This  seems  preferable  to  using  the  singular  form  mos  which 
has  a  different  meaning  and  introduces  a  second  word.  The  organism  is  viewed  as  a 
complex  of  activities  and  processes  and  mores  is  therefore  a  plural  conception. 


34  ENVIRONMENTAL  RELATIONS 

environmental  complex  is  selected  by  a  number  of  species.  All  of  the 
animals  of  a  given  habitat  constitute  what  is  known  as  an  animal 
community;  all  the  life  (plant  and  animal)  is  a  hiota.  It  follows  that 
there  is  often  a  certain  physiological  or  ecological  similarity  in  the  species 
which  select  the  same  or  similar  habitats.  When  not  ecologically 
similar,  animals  living  in  the  same  or  similar  habitats  are  usually 
ecologically  equivalent,  i.e.,  they  meet  the  same  conditions  in  different  ways. 
For  example,  in  a  swift  stream,  the  small  fishes  known  as  darters  maintain 
themselves  against  the  swift  current  by  their  strong  swimming  powers 
and  by  orienting  against  the  current  (positive  rheo taxis).  The  snails 
(Goniobasis)  are  able  to  maintain  themselves  because  of  the  strength  of 
their  foot  and  positive  rheotaxis.  The  darters  and  snails  are  ecologically 
equivalent  with  respect  to  current. 

There  is  a  marked  agreement  of  all  the  animals  of  this  community  in 
their  reactions  to  the  factors  encountered  in  the  stream.  This  agreement 
is  due  (a)  to  the  selection  of  the  habitat  through  innate  (instinctive) 
behavior  (40,  49,  54,  55),  and  (b)  to  the  adjustment  of  behavior  to  the 
conditions  through  the  effects  of  physical  factors  and  through  formation  of 
habits  and  associations  (44,  53). 

Animals  of  the  same  species  show  behavior  differences  in  different 
habitats  (44,  chap,  xxi;  55,  p.  584;  53).  Bohn  found  that  the  sea 
anemones  living  near  the  surface  of  the  sea,  where  the  wave  and  tide 
action  are  strongest,  showed  more  marked  rhythms  of  behavior  in  relation 
to  tide  than  those  living  lower  down  where  the  action  of  the  tide  and 
waves  is  less  marked  (53a,  p.  156;  53  b,  p.  155).  These  rhythms  dis- 
appeared slowly  when  the  animals  wxre  removed  from  the  tide  to  the 
aquarium.  Many  such  cases  are  probably  to  be  found  in  the  natural- 
history  literature.  For  example,  the  chipmunk  differs  in  behavior  under 
different  conditions  (21,  p.  523).  Abbot  (53c,  p.  104)  makes  a  similar 
statement  about  fish.  It  is  apparent  then  that  one  species  may  have 
several  mores.  Different  species  may  sometimes  have  identical  mores; 
these  cases  are  usually  separated  geographically  (55,  p.  604).  In 
addition  to  these  relations,  the  relation  of  ecology  to  species  is  largely  a 
matter  of  language,  names  being  necessary  as  a  means  of  referring  to 
animals. 

The  physiological  and  behavior  relations  of  animals  in  the  same 
community  are  of  much  importance  and  are  included  under  (a)  inter- 
physiology  or  psychology  and  (b)  inter-mores  physiology  or  psychology. 
(a)  Inter-physiology. — Tarde  (55,  citations)  is  the  author  of  the  idea  of 
inter-psychology — the  psychology  of  the  relations  of  individuals  of  the 


PHYSIOLOGY  AND  ECOLOGY  35 

same  species  (man).  He  suggests  that  the  social  psychology  of  man 
may  be  traced  to  the  inter-psychology  and  physiology  of  the  lower 
animals.  If  this  is  true,  then  we  can  be  more  certain  that  the  inter- 
psychology  of  the  higher  forms  has  developed  from  the  inter-physiology 
of  the  lower  forms  (55  and  citations).  To  this  should  be  added  the 
behavior  between  different  species,  while  acting  or  living  together  as 
one.  In  the  steppes  ecologically  similar  animals  frequently  act  as  one 
species.  Mr.  Roosevelt  has  said  that  one  of  the  most  interesting  features 
of  African  wild  life  is  a  close  association  and  companionship  often  seen 
between  totally  different  species  of  game  (3).  Mr.  Roosevelt  shows 
the  zebra  and  hartebeest  herding  together,  {b)  Inter-mores  physiology 
(between  ecologically  dissimilar  forms,  or  antagonistic  forms).— The 
relations  of  animals  of  different  size,  habits,  etc.,  to  one  another  involve 
some  of  the  most  striking  features  of  behavior.  Much  of  the  behavior 
which  tends  to  protect  animals  from  enemies  falls  under  this  head.' 

In  all  cases  of  modification  of  behavior  by  the  physical  environment 
or  by  relations  to  other  animals  of  the  community  and  in  all  cases  where 
the  habitat  is  selected,  the  habitat  is  the  mold  into  which  the  organism 
fits.  The  study  and  analysis  of  the  habitat  is  a  necessity  as  soon  as  the 
selection  of  habitat  and  the  adjustment  of  behavior  and  physiological  makeup 
to  the  environment  are  shown  to  be  general  facts.  Since  habitats  are  differ- 
ent, animal  communities  occupying  different  habitats  are  physiologically 
different  for  the  reasons  just  given. 

The  relations  of  the  animals  which  make  up  communities  are 
relations  of  life  histories.  The  life  histories  of  the  different  species  are  so 
adjusted  to  conditions  that  all  animals  do  not  reach  maturity  and  greatest 
abundance  at  the  same  time.  Some  species  continue  throughout  the 
season;  for  example,  mammals  because  of  their  long  lives,  and  some 
species  of  aphids  or  copepods  because  of  their  great  fecundity  and 
peculiar  physiological  makeup.  There  is  a  succession  of  mature  or 
breeding  animals  with  the  change  of  season.  A  similar  phenomenon 
is  noticeable  in  plants.  Such  succession  is  called  seasonal  succession 
(47.  56).  Different  species  of  the  same  community  come  into  relation 
at  different  seasons  of  the  year. 

Communities  are  systems  of  correlated  working  parts.  Changes  are 
going  on  all  the  time  as  a  sort  of  rhythm  much  like  the  rhythm  of  activity 
in  our  own  bodies  related  to  day  and  night.  In  addition  to  this,  com- 
munities grow   by   the   addition  of  more  species,   decline,   and  finally 

'  It  is  at  this  point  that  ecology  comes  into  contact  with  the  theories  of  natural 
selection,  adaptation,  mimicry,  etc. 


$6  ENVIRONMENTAL  RELATIONS 

disappear  from  the  locality  with  changes  in  environment  produced 
either  by  themselves  or  by  physiographic  or  climatic  changes  (57,  58). 
The  general  growth  or  evolution  of  environmental  conditions  and 
the  communities  which  belong  to  them,  are  included  under  succession. 
The  word  succession  is  used  in  three  distinct  senses.  We  speak  of 
(c)  geological  succession,  (b)  seasonal  succession,  and  (c)  ecological 
succession. 

a)  Geological  succession  is  primarily  a  succession  of  species  through- 
out a  period  or  periods  of  geological  time.  It  is  due  mainly  to  the 
dying-out  of  one  set  of  species  and  the  evolution  of  others  which  take 
their  places,  or  in  some  cases  to  migration. 

b)  Seasonal  succession  is  the  succession  of  species  or  stages  in  the  life 
histories  of  species  over  a  given  locality,  due  to  hereditary  and  environic 
differences  in  the  life  histories  (time  of  appearance)  of  species  living  there. 

c)  Ecological  succession  of  animals  is  succession  of  mores  over  a  given 
locality  as  conditions  change.  If  species  have  relatively  fixed  mores  we 
have  succession  of  species.  When  mores  are  flexible  we  may  have  the 
same  species  remaining  throughout,  with  changes  in  mores.  It  is  on  the 
basis  of  ecological  succession  that  we  arrange  the  data  presented  in  chaps, 
iv  to  xiv  and  proceed  with  discussion.  The  response  of  the  organism 
to  the  condition  of  the  environment  is  only  occasionally  or  partially 
dependent  upon  ecological  succession,  but  this  is  the  only  notable 
phenomenon  about  which  habitats  and  animal  communities  can  be 
arranged  into  a  natural  order. 

2.      CLASSIFICATION   OF   COMMUNITIES 

Ecological  classification  of  animals  must  be  based  upon  community 
or  similarity  of  physiological  makeup,  behavior,  and  mode  of  life.  Those 
natural  groups  of  animals  which  possess  likenesses  are  the  communities 
which  we  must  recognize.  One  community  ends  and  another  begins 
where  we  find  a  general  more  or  less  striking  difference  in  the  larger  mores 
characters  of  the  organisms  concerned.  These  communities  usually 
occupy  relatively  uniform  environments  (58a). 

a)  Ecological  terminology  (13). — Terminology  in  ecology  is  still 
unsettled  and  changing.  Groupings  have  thus  far  been  based  upon 
similarity  of  habitat.  Habitat  likenesses  have  in  general  been  based 
upon  general  resemblances.  General  resemblances  have  not  always  been 
accompanied  by  similar  physical  conditions.  In  general  there  has 
been  an  agreement  in  the  recognition  of  strata,  of  associations  as  com- 


COMMUNITIES  37 

munities  based  upon  minor  differences  in  habitats,  and  formations  based 
upon  larger  major  differences  in  habitats. 

We  give  the  communities  of  different  orders  below  with  taxonomic 
divisions  of  corresponding  magnitude  opposite  for  comparison.  With 
the  exception  of  the  first,  these  taxonomic  groupings  do  not  bear  the 
slightest  relation  to  the  ecological  groupings,  but  are  added  to  indicate 
magnitude. 

Ecological  Groups  Taxonomic  Groups 

{Mos)  mores  Form  (forms)  (species) 

Consocies  Genus 

Stratum  or  story  Family 

Association  or  society  Order 

Formation  Class 

Extensive  formation  Phylum 

(Aquatic  and  terrestrial)  (Vertebrates  and  invertebrates) 

Mores,  in  the  technical  sense  in  which  the  term  is  used  here,  are 
groups  of  organisms  in  full  agreement  as  to  physiological  life  histories 
as  shown  by  the  details  of  habitat  preference,  time  of  reproduction, 
reactions  to  physical  factors  of  the  environment,  etc.  The  organisms 
constituting  a  mores  usually  belong  to  a  single  species  but  may  include 
more  than  one  species  as  specificities  of  behavior  are  not  significant  (13). 

Consocies  are  groups  of  mores  usually  dominated  by  one  or  two  of  the 
mores  concerned  and  in  agreement  as  to  the  main  features  of  habitat 
preference,  reaction  to  physical  factors,  time  of  reproduction,  etc. 
Example:  the  prairie  aphid  consocies.  The  aphids  dominate  a  group 
of  organisms  which  for  the  most  part  prey  upon  them,  as,  for  instance, 
certain  species  of  lacewing,  lady  beetles,  syrphus-flies,  etc.  (13). 

Strata  are  groups  of  consocies  occupying  the  recognizable  vertical 
divisions  of  a  uniform  area.  Strata  are  in  agreement  as  to  material  for 
abode  and  general  physical  conditions  but  in  less  detail  than  the  consocies 
which  constitute  them  (13). 

For  example,  a  forest-animal  community  is  clearly  divisible  into  the 
subterranean-ground  stratum,  field  stratum  (zone  of  the  tops  of  the 
herbaceous  vegetation),  the  shrub  stratum  (zone  of  the  tops  of  the 
dominant  shrubs),  the  lower  tree  stratum  (zone  of  the  shaded  branches 
of  the  trees),  and  the  upper  tree  stratum.  A  given  animal  is  classified 
primarily  with  the  stratum  in  which  it  breeds,  as  being  most  important 
to  it,  and  secondarily  with  the  stratum  in  which  it  feeds,  etc.,  as  in  many 
cases  most  important  to  other  animals.     The  migration  of  animals  from 


38  ENVIRONMENTAL  RELATIONS 

one  stratum  to  another  makes  the  division  lines  difficult  to  draw  in  some 
cases.  Still,  the  recognition  of  strata  is  essential  but  a  rigid  classification 
undesirable.  Consocies  boring  into  the  wood  of  living  trees  probably 
should  be  considered  as  consocies  relatively  independent  of  stratification 
phenomena  (13). 

Associations  are  groups  of  strata  uniform  over  a  considerable  area. 
The  majority  of  mores,  consocies,  and  strata  are  different  in  different 
associations.  A  minority  of  strata  may  be  similar.  The  term  is  applied 
in  particular  to  stages  of  formation  development  of  this  ranking.  The 
unity  of  associations  is  dependent  upon  the  migration  of  the  same  indi- 
vidual and  the  same  mores  from  one  stratum  to  another  at  different  times 
of  day  or  at  different  periods  of  their  life  histories.  Migration  is  far 
more  frequent  from  stratum  to  stratum  than  from  one  association  to 
another  (13). 

Formations  are  groups  of  physiologically  similar  associations.  For- 
mations differ  from  one  another  in  all  strata,  no  two  being  closely 
similar.  The  number  of  species  common  to  two  formations  is  usually 
small  (e.g.,  5  per  cent).  Migrations  of  individuals  from  one  formation 
to  another  are  relatively  rare  (13). 

Extensive  formations  are  groups  of  formations  clearly  influenced  by  a 
given  climate  in  the  case  of  land  formations  and  by  the  topographic  age 
of  a  large  area  and  by  climate  in  the  case  of  aquatic  formations  (13,  58a). 

A  sub-formation  is  an  association  or  a  poorly  developed  phase  of  a 
formation.  The  term  is  used  in  comparing  communities  of  the  ranking 
associations  when  viewed  from  the  standpoint  of  physiological  differ- 
ences but  without  reference  to  genetic  history.  Accordingly  the  same 
community  is  referred  to  as  an  association  in  the  genetic  sense  and  a 
sub-formation  when  the  point  of  view^  is  that  of  physiological  difference 
or  resemblance. 

b)  Animal  communities  of  the  forest-border  region. — The  forest-border 
region  is  the  western  line  of  demarkation  between  forest  and  steppe  (see 
prairie  area  of  Fig.  8,  p.  51).  The  following  is  a  list  of  the  chief  animal 
communities  of  the  area  about  the  south  end  of  Lake  Michigan.  It  is 
not  intended  to  be  complete,  but  rather  to  illustrate  the  use  of  the  terms 
with  particular  reference  to  the  communities  to  be  mentioned  later  on. 
The  term  community  is  used  in  the  general  sense.  Association  is 
applied  to  stages  in  genetic  development,  with  sub-formation  as  an 
alternative  as  defined  above.  The  classification  here  presented  in  outline 
is  artificial  and  attempts  to  combine  the  historical  or  genetic  with  the 


COMMUNITIES 


39 


purely  physiological  points  of  view.     Accordingly  some  communities  are 
mentioned  more  than  once.     Others  have  two  names. 

I.    Stream  Communities 

1.  Intermittent  stream  communities 

a)  Intermittent  rapids  consocies 

b)  Intermittent  pool  consocies 

c)  Permanent  pool,  or  horned  dace  association 

2.  Permanent  stream  communities 
a)  Spring  dominated  stages 

i)  Spring  consocies 

2)  Spring  brook  associations 

3.  Creek  and  river  communities 

a)  Pelagic  sub-formation 

b)  Hydropsyche,  or  rapids  formation  (turbulent-water  formations) 

c)  Anodontoides  ferussacianus,  or  sand  or  gravel-bottom  formations 

d)  Sandy-bottomed    stream    sub-formation     (shifting-bottom     sub- 
formations) 

e)  Silt  or  sluggish-stream  communities 
i)  Sluggish-creek  sub-formations 

2)  Pelagic  formations 

3)  Hexagenia,  or  silt-bottom  formation 

4)  Planorbis  bicarinatus,  or  vegetation  formation 

II.    Large  Lake  Communities 

1.  Pelagic  formations 

2.  Eroding  rocky-shore  sub-formations  (turbulent-water  formations) 

3.  Depositing  sandy-shore  sub-formations  (shifting-bottom  sub-forma- 
tions) 

4.  Lower-shore  formations 

5.  Deep-water  formations 

III.  Lake-Pond  Communities 

1 .  Pelagic  sub-formations 

2.  Pleurocera  subulare,  or  terrigenous-bottom  formation 

3.  Vegetation  formation 

a)  Leptocerinae ,  or  submerged  vegetation  association 

b)  Neuroma,  or  emerging  vegetation  association 

4.  Temporary  pond  formations 

IV.  Prairie  or  Grassland  Formation  of  the  Savanna  Climate 

1.  Xiphidium  fasciaium,  or  grassland  association  of  moist  ground  and 
marsh  vegetation  in  the  savanna  and  forest  climates 

2.  Prairie  chicken,  or  high-prairie  association  of  the  savanna  climate 


40  ENVIRONMENTAL  RELATIONS 

V.  Thicket  or  Forest  Margin  Sub-Formations  of  the  Savanna  and  Forest 
Climates.  Physiological  group  in  the  main  though  the  "  candlehead " 
sub-formation  may  develop  into  V,  2,  or  VI,  7,  d 

1.  Wet-ground  thicket  sub-formations  (lower  strata  periodically  sub- 
merged) 

a)  River  deposit  or  stream-margin  thicket  sub-formations.     Associa- 
tion in  the  development  of  flood-plain  forest 

b)  Marsh  and  pond-margin  thicket  sub-formations  (first  association 
in  the  development  of  forests  in  marshes) 

c)  Candlehead  or  moist  forest  margin  sub-formation  of  the  savanna 
and  deciduous  forest  climates 

2.  Straussia  longipennis,  or  high  forest  margin  sub-formation  of  the 
savanna  climate  (a  climatic  sub-formation  of  considerable  permanency, 
probably  not  usually  a  genetic  type) 

VI,    Forest  Communities  of  the  Deciduous  Forest  Climate 

1.  Elm-ash  series  of  communities 

a)  Low  prairie  associations  (see  IV,  i) 

b)  Marsh-margin  thicket  associations  (see  V,  i,b) 

c)  Elm-ash  associations 

2.  Tamarack  or  floating-bog  series  of  communities 

a)  Low  prairie  or  floating-bog  association  (pitcher-plant  consocies) 

b)  Marsh-margin  thicket  associations  (see  \,  1,  b) 

c)  Tamarack-forest  formations 

3.  Flood-plain  series  of  communities 

a)  Terrigenous  river-margin  associations 

b)  Stream-margin  thicket  associations  (see  V,  1,  a) 

c)  Elm  and  river-maple  associations  (not  studies) 

4.  Clay  series  of  communities 

c)  Cicindela  purpurea  limbalis,  or  bare  clay  association 

b)  Sweet-clover  association 

c)  High  forest  margin  associations  (see  V,  2) 

5.  Rock  series  of  communities  (little  studied) 

a)  Bare  rock  consocies 

b)  Thicket  association  (probably  high  forest  margin,  V,  2).    Later 
stages  not  well  represented  near  Chicago 

6.  Sand  series  of  communities 

a)  Lake-margin  association 

b)  Cicindela  lepida,  or  Cottonwood  association 

c)  Cicindela  lecontei,  or  the  pine  association 

d)  Ant-lion  or  black-oak  association 

7.  Climatic  forest  formation  of  the  deciduous  forest  climate 
a)  Birch-maple  association  of  the  tamarack-forest  series 

h)  Panorpa,  or  oak-elm-basswood  association  of  the  flood-plain  and 
marsh-forest  series 


COMMUNITIES  41 

c)  Hyaliodes  vitripennis,  or  black-oak,  red-oak  association  of  the  sand 
and  other  sterile  soil  series 

d)  Cicindela  sexguttata,  or  red-oak,  hickory  association  (climax,  or  final 
forest  association  of  the  savanna  climate) 

e)  Wood-frog  or  beech-maple  association  (the  climax  or  final  associa- 
tion of  the  forest  climate) 

The  evidence  for  the  relations  of  the  different  formations  and 
associations  here  suggested  is  presented  from  time  to  time  in  the  following 
pages,  and  on  the  basis  of  this>  is  graphically  represented  in  Diagram  9, 
on  p.  312,  where  both  physiological  and  genetic  relations  are  indicated. 


CHAPTER  III 

THE  ANIMAL  ENVIRONMENT:    ITS  GENERAL  NATURE  AND  ITS 
CHARACTER  IN  THE  AREA  OF  STUDY 

I.    Nature  and  Classification  of  Environments  (35a,  55,  58)' 

The  environment  is  a  complex  of  many  factors,  each  dependent 
upon  another,  or  upon  several  others,  in  such  a  way  that  a  change  in  any 
one  efifects  changes  in  one  or  more  others.  The  most  important  environ- 
mental factors  are  water,  atmospheric  moisture,  light,  temperature, 
pressure,  oxygen,  carbon  dioxide,  nitrogen,  food,  enemies,  materials 
used  in  abodes,  etc.  In  nature  the  combinations  of  these  in  proportions 
requisite  for  the  abode  of  a  considerable  number  of  animals  are  called 
"environmental  complexes"  (55).  It  is  our  purpose  to  consider  animals 
as  inhabiting  environmental  complexes,  rather  than  to  isolate  their 
responses  to  various  single  factors.  The  consideration  of  environmental 
complexes  in  any  comprehensive  way  would  consume  much  space  and 
require  extensive  and  special  knowledge  of  many  fields.  Accordingly, 
we  can  present  here  only  the  briefest  outline  of  some  of  the  principles  of 
classification,  and  the  important  features. 

If  one  is  to  understand  the  most  elementary  principle  of  the  classi- 
fication of  environments,  he  must  recognize  the  distinction  between 
local  and  (55,  58a)  climatic  environmental  complexes.  Local  complexes 
are  often  referred  to  as  secondary  or  minor  conditions  or  as  edaphic  or 
soil  conditions.  The  climate,  and  such  features  as  types  of  vegetation 
covering  large  areas,  e.g.,  steppe,  deciduous  forest,  etc.,  are  commonly 
regarded  as  climatic.  Opposed  to  these,  and  lying  within  them,  are  the 
local  conditions,  such  as  streams,  lakes,  soils,  exposure,  etc,  which  are 
only  indirectly  dependent  upon  climate.  The  idea  can  be  better  illus- 
trated by  the  desert  than  by  our  own  region.  For  example,  in  the 
Mohave  Desert,  the  climatic  conditions  may  be  characterized  as  hot 
and  arid.  Within  this  desert  are  a  few  streams  fed  by  mountain  rain- 
fall. These  streams  are  local  conditions  in  themselves,  and  produce 
others,  such  as  moist  soil,  and  types  of  vegetation  which  do  not  belong 
to  the  desert.  Within  the  area  about  Chicago  are  represented  two 
geographic  complexes,  the  savanna  and  the  deciduous  forest,  and  lying 

'  Numbers  in  the  text  in  parentheses  refer  to  references  in  the  Bibliography 
(PP-  325-36). 

42 


FACTORS  43 

in  and  among  these  are  \'arious  local  complexes.  The  history  to  follow 
applies  particularly  to  the  local  complexes.  The  analysis  into  factors 
applies  to  both  local  and  climatic. 

II.    The  Important  Factors  and  Their  Control  in  Nature 

Little  experimentation  has  been  conducted  with  a  view  to  determin- 
ing the  relative  importance  of  different  factors  in  the  control  of  animals 
within  an  environmental  complex.  It  is  known,  however,  that  moisture 
(evaporating  power  of  the  air),  light,  and  materials  for  abode  are  factors 
important  in  the  life  of  land  animals;  carbon  dioxide,  oxygen,  materials 
for  abode  (including  bottom),  and  current,  in  the  life  of  aquatic  animals. 
The  evidence  for  these  statements  cannot  be  presented  here,  but  will  be 
given  in  appropriate  places  throughout  the  discussion  which  follows. 

I.      THE   CONTROL   OF   FACTORS 

This  is  related  to  physiography,  surface  geology,  and  vegetation. 

a)  Physiography. — In  streams,  current  and  oxygen  content  are 
determined  very  largely  by  physiographic  conditions.  Current  is  a 
function  of  volume  of  water  and  slope  of  stream  bed.  Oxygen  content 
is  largely  determined  by  the  rate  of  flow,  and  therefore  is  influenced  by 
physiography.  In  lakes,  oxygen  content  is  determined  by  the  depth, 
the  temperature,  and  winds — ^physiographic  factors  are  again  important. 
On  land,  moisture  and  light  are  in  a  measure  controlled  by  physiographic 
features.  Slope  and  direction  of  facing  profoundly  affect  vegetation, 
moisture,  and  light. 

b)  Surface  materials  and  vegetation. — Materials  for  abode  are  largely 
the  surface  soil  or  rock  or  the  vegetation.  Surface  soil  or  rock  influences 
the  moisture.  Both  moisture  and  surface  materials  influence  the  kind 
and  amount  of  vegetation.     All  are  interdependent  (350). 

Physiographic  features  change  with  time.  Erosion  changes  the 
gradient  of  streams,  the  width  of  valleys,  the  steepness  of  valley  walls 
and  cliffs,  the  ground-water  level,  etc.  The  weathering  of  rock  is  a 
process  familiar  to  all.  It  is  the  aggregate  of  processes  by  which  the 
coarse  and  hard  or  massive  materials  are  reduced  to  clay  and  soil.  This 
requires  time. 

The  fact  that  vegetation  grows  upon  the  so-called  sterile,  coarse, 
rough-surface  materials,  usually  scattered  or  ephemeral  at  first,  but 
increasing  in  denseness  with  each  generation,  is  also  familiar  (58), 
Plants  add  organic  matter  to  the  soil.  This  organic  matter  holds  the 
water  so  that  moisture  increases  and  plants  may  increase.     With  such 


44  ANIMAL  ENVIRONMENT 

changes  it  is  obvious  that  an  area  of  sterile  soil  will  support  more  animals 
as  time  goes  on,  than  at  the  outset,  when  the  conditions  were  such  that 
only  a  few  hardy  species  could  live.  Here  again,  then,  time  is  the  impor- 
tant factor  in  determining  the  change  of  the  area,  so  as  to  be  suitable 
for  more  species  (because  more  species  are  adapted  to  live  in  the  result- 
ing than  in  the  initial  conditions).  The  length  of  time  which  has 
elapsed  since  a  given  set  of  surface  and  physiographic  conditions  became 
exposed  to  the  atmosphere  is  very  important  in  governing  the  number, 
kind,  and  distribution  of  animals  in  a  given  area. 

c)  The  value  of  physiographic  form. — Physiographic  features  are 
classified  according  to  their  form  and  their  mode  of  origin.  What  is  the 
importance  of  their  forms  and  modes  of  origin  to  the  animal  ecologist  ? 
Has  a  kame  or  an  esker  or  a  valley  train  any  significance  so  far  as  animals 
are  concerned?  So  far  as  anyone  has  been  able  to  observe,  the  fact 
that  they  possess  their  particular  form  is  of  no  significance  whatever. 
Their  relations  to  present  ground-water  level,  their  slope,  relation  to  the 
sun,  etc.,  are  significant.  The  amount  of  surface  soil  and  the  denseness 
of  vegetation  are  also  of  very  great  importance,  and  conditions  in  these 
respects  are  usually  closely  correlated  with  the  length  of  time  that  the 
structures  have  been  exposed  to  the  atmosphere. 

Since  age  is  important,  we  turn  at  once  to  the  history  of  an  area  in 
order  to  learn  the  relative  age  of  the  various  features  present.  We  have 
parted  company  with  the  physiographer  and  his  discussion  of  mode  of 
origin,  and  are  interested  in  origins  only  in  point  of  time. 

III.    History  of  the  Region  about  Lake  Michigan  (59) 
I.    physiographic  history 

We  will  give  the  briefest  possible  account  of  the  history  of  the  Chicago 
area,  following  Leverett  (59),  Salisbury  (57,  60),  Alden  (61),  Atwood 
(62),  Goldthwait  (62,  63,  64),  and  Lane  (65). 

The  most  important  features  of  our  area  were  shaped  during  and 
since  the  glacial  epoch.  To  us,  the  only  important  movement  of  the 
ice  was  that  of  the  last  Wisconsin  ice  sheet.  This  came  to  us  mainly 
from  the  east  and  north.  It  spread  out  over  the  great  basins  now 
occupied  by  the  Great  Lakes  and  thence  pushed  on  to  the  higher  rock  to 
the  south  of  them  and  reached  its  southernmost  extent  in  Southern 
Illinois. 

In  retiring  from  here  (Fig.  i)  one  of  the  positions  in  which  the 
edge  of  the  ice  halted  corresponded  to  the  present  Valparaiso  Moraine. 
The  crest  of  this  moraine  extends  from  the  Fox  Lake  region  (see  map) 


FACTORS 


45 


^ 

W 

1 

r 

% 

•'  SHEET /;  ^ 

1                V-T~.-- 

■^ 

^ 

f, 

:^^ 

^r" 

4 
A.-.. 

-  — 

The  History  of  the  Chicago  Region 

Fig.  I. — Showing  the  region  of  the  Great  Lakes  when  the  Wisconsin  ice  sheet 
was  retreating  from  its  maximum  extent  (after  Atwood  and  Goldthwait). 

Fig.  2. — A  part  of  the  same  area,  showing  the  drainage  of  the  ice  sheet  by  the 
Kankakee  and  Huron  rivers  through  Dowagiac  Lake  (from  Lane  after  Leverett). 

Fig.  3.— Showing  a  later  stage  of  the  retreat  of  the  ice  sheet— the  Glenwood 
stage  (from  Lane  after  Leverett). 

Fig.  4.— a  later  stage  of  the  same— the  Calumet  stage  of  Lake  Chicago  (from 
Goldthwait  after  Leverett  and  Taylor) . 

Fig.  5.— a  still  later  stage— probably  the  Tolleston  stage  (from  Lane  after 
Leverett) . 

Fig.  6. — A  post-Tolleston  stage  (from  Goldthwait  and  Atwood  after  Leverett 
and  Taylor). 


46  ANIMAL  ENVIRONMENT 

southward  around  the  head  of  Lake  Michigan,  nearly  parallel  with  the 
shore,  then  northward  into  Michigan,  there  turning  somewhat  more  to 
the  east  (Fig.  2).  Beyond  the  edge  of  the  ice,  early  lines  of  drainage  were 
established  and  temporary  lakes  came  into  existence.  All  of  our  south- 
ward flowing  rivers  bore  the  sediment-laden  waters  from  the  melting  ice. 
The  results  of  this  may  be  seen  in  the  gravel  and  sand  outwash,  valley 
trains,  etc.,  along  the  DuPage  and  other  rivers,  the  more  sandy  portion 
usually  being  farthest  downstream. 

In  Southwestern  Michigan,  these  early  lines  of  drainage  were  by 
the  St.  Joseph  and  the  Dowagiac  valleys.  In  the  latter  a  small  lake  is 
believed  to  have  existed  (Fig.  2).  These  waters  did  not  flow  into  the 
south  end  of  the  lake,  as  at  present,  but  united  and  flowed  down  the 
present  course  of  the  Kankakee  River.  The  Kankakee  marsh  area  and 
the  region  at  the  mouth  of  the  Kankakee  (Morris  Basin)  are  believed 
to  have  been  occupied  by  a  lake.  These  basins  are  surrounded  by  sand 
areas  which  are  probably  the  oldest  in  our  area  of  study.  Dunes  are 
said  to  be  present  to  the  south  and  east  of  "Lake  Kankakee,"  a  few  being 
present  on  the  moraine  in  the  extreme  southeast  corner  of  our  map 
(frontispiece). 

The  next  stage  was  marked  by  the  retirement  of  the  ice  from  the 
position  of  the  Valparaiso  Moraine  to  the  present  basin  of  Lake  Michigan. 
The  drainage  of  glacial  waters  down  the  Fox,  DuPage,  and  Upper 
DesPlaines  rivers  stopped  (Fig.  3).  The  lakes  to  the  south  and  east 
probably  began  to  disappear.  Later,  the  St.  Joseph  and  Dowagiac 
changed  their  lower  courses  and  flowed  directly  into  Lake  Michigan, 
which  found  an  outlet  by  way  of  the  lower  DesPlaines. 

Now  begins  the  history  treated  in  the  first  bulletin  of  the  Geographic 
Society  (60),  and  Bulletin  7  of  the  Illinois  Geological  Survey  and  else- 
where (6 1 ,  6 2 ,  63 ,  64) .  The  predecessor  of  Lake  Michigan  stood  at  a  level 
55  to  60  feet  above  the  present  lake.  The  stage  is  known  as  the  Glen- 
wood  stage  of  Lake  Chicago.  Cliffs  were  cut,  beaches  of  sand  and  gravel 
were  deposited,  and  dunes  were  formed.  These  are  our  second  oldest 
sand  and  gravel  areas.     Their  position  is  shown  on  the  map  (facing  p.  52). 

The  water  then  fell  to  a  level  of  35-40  feet  above  the  present  lake. 
This  is  known  as  the  Calumet  stage  (Fig.  4).  Here  again  cliffs  and 
beaches  of  sand  and  gravel  were  formed,  and  constitute  our  third  in 
point  of  age.  These  beaches  have  not  been  indicated  on  the  map 
because  their  distribution  within  the  state  of  Michigan  has  not  been 
studied  by  physiographers.  In  the  vicinity  of  Waukegan  they  are  very 
close  to  the  Glenwood  beach. 


FACTORS  47 

The  lake  again  receded,  probably  to  a  low  level,  and  readvanced  to 
a  2o-foot  level  known  as  the  Tolleston  stage  (Fig.  5).  Here  the  develop- 
ment of  beaches  continued  and  the  cutting  of  new  clilTs  was  inaugurated. 
From  these  beaches,  dunes  were  developed  which  are  fourth  in  point 
of  age.  The  position  of  these  beaches  is  not  indicated  on  the  map. 
The  lake  is  believed  to  have  fallen  after  this  to  a  level  of  60  feet  below 
the  present  level  of  Lake  Michigan  (60-62),  which  is  known  as  the  Cham- 
plain  stage.  At  this  time  the  sea  came  up  the  Gulf  of  St.  Lawrence  as 
far  as  Lake  Ontario.  Since  the  cliffs  and  beaches  of  this  stage  were 
again  submerged,  they  are  no  doubt  of  some  importance  to  the  aquatic 
life  in  Lake  Michigan,  because  they  affected  slope  and  bottom  locally. 
The  water  rose  again  to  a  level  12  to  15  feet  above  the  present  lake, 
known  as  the  Algonquin  or  post-Tolleston  stage  (Fig.  6),  which  was 
followed  by  a  retreat  to  the  present  level. 

2.       THE    FORMER   CLIMATE   AND   ANIMALS    (66) 

During  the  ice  age,  the  entire  region  about  Chicago  was  overridden 
by  the  ice,  and  plants  and  animals  migrated  southward.  There  are  at 
present  a  few  animal  species  which  inhabit  glaciers  and  ice  fields,  and 
probably  such  were  the  only  regular  inhabitants  at  that  time.  The 
tundra  and  coniferous  forest  were  crowded  to  the  southward,  and  with 
them  the  caribou,  musk  ox,  and  other  northern  animals.  As  the  ice 
retreated  north  of  the  southern  end  of  the  basin  of  Lake  Michigan  and 
the  Lake  Chicago  stage  was  inaugurated,  a  tundra  climate  no  doubt 
prevailed  in  the  Valparaiso  Moraine.  It  was  probably  the  breeding- 
place  of  the  present  tundra  species  of  birds;  the  home  of  the  musk  ox, 
the  caribou,  the  snow  grouse,  and  other  northern  animals.  The  ponds 
grew  aquatic  plants  and  probably  supported  hordes  of  mosquitoes  (2) 
and  other  aquatic  insects  in  summer.  Early  Lake  Chicago  is  said  to 
show  no  evidence  of  life.  If  we  may  judge  from  Arctic  lakes  at  present, 
it  had  a  summer  fauna,  especially  of  small  crustaceans  and  probably 
some  fishes. 

As  the  ice  retreated  still  farther  northward,  the  coniferous  forest 
displaced  the  tundra,  and  the  musk  ox  and  caribou  were  presumably 
only  winter  visitors;  the  woodland  caribou  and  the  moose  were  probably 
regular  residents.  Conditions  in  the  lake  were  similar  to  those  of  the 
preceding  stage.  By  this  time  a  relatively  rich  flora  and  fauna  probably 
existed.  Organic  material  accumulated  in  the  soil,  shade  was  produced, 
etc.  With  the  further  retreat  of  the  ice,  the  coniferous  forest  continued 
for  a  long  time,  but  the  plants  and  animals  became  gradually  more  and 


48  ANIMAL  ENVIRONMENT 

more  like  those  of  the  southern  portion  of  the  coniferous  forest  (67), 
and  gradually  gave  way  through  processes  of  ecological  succession  to 
the  species  of  the  present  day.  Just  preceding  our  period,  the  mastodon 
roamed  over  the  site  of  Chicago.  The  skeleton  of  one  of  these  was 
found  in  a  marsh  near  Crown  Point,  Ind.,  another  at  Cary,  111. 

IV.    Extent  and  Topography  of  the  Area  Considered' 

The  area  which  we  shall  consider  has  its  center  at  a  point  18  miles 
east  of  Lincoln  Park.  It  extends  67  miles  (108.  i  kilometers)  to  the  east 
and  to  the  west  and  40  miles  (64.4  kilometers)  to  the  north  and  40  miles 
to  the  south  from  this  point.  Measured  from  the  mouth  of  the  Chicago 
River  it  extends  85  miles  (137  kilometers)  eastward,  49  miles  (79  kilo- 
meters) westward,  38  miles  (61  kilometers)  southward,  and  42  miles 
(68  kilometers)  northward.  It  is  80  by  134  miles  (128.8  by  216  kilo- 
meters) and  contains  over  10,700  sq.  miles  (27,820  sq.  kilometers). 

The  range  of  altitude  in  the  Chicago  area  is  not  great.  The  lowest 
part  of  the  bottom  of  the  lake  included  in  our  map  is  about  80  feet  above 
sea-level.  The  highest  point  on  the  Valparaiso  Moraine  is  900  feet 
above  sea-level,  which  gives  a  range  of  altitude  of  820  feet.  The  surface 
of  the  lake  is  581  feet  above  sea-level.     The  plain  of  Lake  Chicago  is 

'  See  frontispiece  map.  The  term  "  Chicago  Area  "  has  been  appUed  to  regions 
varying  in  extent  and  direction,  according  to  the  points  of  view  and  interests  of 
various  authors.  Chicago  biologists  have  as  yet  written  but  little  concerning  the 
ecology  of  areas  to  the  east  of  Millers,  Ind.  It  becomes  necessary  to  go  farther  from 
Chicago  every  year.  The  areas  in  Michigan  and  Northern  Indiana  offer  the  only 
substitute  for  those  nearer  to  Chicago  which  are  being  so  rapidly  destroyed. 

The  following  maps  covering  the  area  have  been  published: 

1.  Lake  Michigan 

a)  U.S.  Hydrographic  Office,  Maps  Nos.  1467-75. 

b)  U.S.  Lake  Survey  Maps,  Custom  House  Bldg.,  Detroit,  Mich. 

2.  Land 

a)  County  surveyors  often   publish  maps   covering  particular   counties,   e.g., 
LaPorte  Co.,  Ind. 

b)  lUinois  Internal  Improvement  Committee,  The  Water-Way  Report,  Springfield, 
1909. 

c)  Topographic  sheets  of  the  U.S.  Geological  Survey  (prepared  for  much  of  the 
region  covered  by  our  map). 

d)  The  U.S.  Land  Office  has  maps  of  the  original  land  surveys  which  are  said  to . 
give  roughly  the  distribution  of  prairies,  forests,  and  marshes. 

e)  Rand  McNally  &  Co.  publish  maps  of  all  local  counties. 
/)   Brown  &  Windes'  (Chicago)  map  of  the  Fox  Lake  Region. 

g)   Davis,  "Peat"  (map  of  marshes),  Ann.  Rept.  Mich.  Geol.  Siirv.,  1906. 


AREA  OF  STUDY 


49 


chiefly  between  581  and  600  feet,  and  presents  very  little  relief.  The 
lowest  point  of  land  on  our  map  is  in  the  valley  of  the  Illinois  River 
below  the  entrance  of  the  Kankakee.  This  is  480  feet  above  tide,  or 
loi  feet  below  the  level  of  Lake  Michigan.  In  passing  from  the  lowest 
point  in  the  lake  shown  on  our  map  to  the  vicinity  of  Lake  Zurich,  which 
is  the  location  of  one  of  the  high  points  on  the  moraine,  one  would 
travel  64  miles  and  make  an  ascent  of  only  12  feet  per  mile  on  the 
average.  Indeed,  if  Lake  Michigan  were  to  become  dry  and  its  bottom 
a  prairie,  it  would  appear  an  undulating  plain. 


V.     Climate  and  Vegetation  of  the  Area 

I.    meteorological  conditions  affecting  animals  (68) 

The  table  (I)  illustrates  the  fact  that  there  are  some  notable  differ- 
ences between  the  different  parts  of  our  area.     Extreme  points  would 

TABLE  I 


Temperature 

Mean  Rainfall 

Sunshine 

Ratio  of 
Rainfall  to 
Evaporation 

Station 

April  to  September 

Year 

April 
to  Sep- 
tember 

Year 

April 
to  Sep- 
tember 

Year 

July. 

1887, to 

July. 

1888 

Mean 

Mean  of 
Maxima 

Mean  of 
Minima 

Mean 

Chicago .  .  . 
South  Bend 

62.6 
653 

70.0 
76.3 

55.6 
54-3 

48 
49 

193 
18.3 

33-4 
34-5 

1695 
hrs. 

2616 
hrs. 

.... 

95% 
105% 

show  greater  differences.  The  evaporating  power  of  the  air  is  probably 
one  of  the  best  indices  of  conditions  which  affect  animals.  The  ratio  of 
rainfall  to  evaporation  is  the  only  expression  of  the  evaporating  power 
of  the  air  which  has  been  mapped.  Fig.  7  shows  this  phenomenon  in 
Central  North  America,  with  our  area  indicated. 

2.      VEGETATION    (69,    70) 

Those  features  of  the  vegetation  which  are  called  climatic  must  be 
discussed  first.  The  two  main  climatic  divisions  of  vegetation  represented 
in  the  Chicago  area  are  savanna  including  the  prairie  vegetation,  and 
deciduous  forest.  The  prairie,  or  savanna,  as  distinguished  from  steppe, 
is  a  strip  of  country  (the  forest-border  area)  a  few  hundred  miles  wide, 
from  Athabaska  to  Texas,  where  trees,  chiefly  oak,  hickory,  basswood, 


so 


ANIMAL  ENVIRONMENT 


and  elm,  occur  in  groves  and  along  streams.  It  has  the  general  form  of  a 
bow,  with  its  central  and  most  eastern  point  at  Chicago  (Fig.  8).  To  the 
east  of  Valparaiso,  Ind.,  the  forest  is  chiefly  beech  and  maple  (see 
frontispiece).  The  types  are  believed  to  stand  in  close  relation  to 
climate,  especially  to  ratio  of  rainfall  to  evaporation  (Fig.  7).^ 

The  vegetation  of  local  conditions,  as  indicated  on  p.  42,  is  different 
from  that  of  the  region  as  a  whole  and  we  are  concerned  in  part  with 


Fig.  7. — Map  showing  ratio  of  rainfall  to  evaporation  in  percentages,  with  area 
of  special  study  inclosed  in  rectangle  (after  Transeau).  Compare  with  Sargent's 
map  of  the  "Forests  of  North  America"  (loth  Census  Report  and.  Fig.  8  below). 

the  relations  of  the  animal  communities  of  local  conditions  to  animal 
communities  of  the  climatic  vegetation. 

VI.    Localities  of  Study 

In  beginning  the  investigation  of  any  biological  subject  from  the 
point  of  view  of  general  principles,  the  most  important  step  is  the  selec- 
tion of  the  material  (animals  to  be  studied).     In  ecological  work  we 

'  A  glance  at  the  map  shows  us  that  our  area  of  study  is  in  the  center  of  the 
Forest-Border  Region. 


LOCALITIES  STUDIED 


51 


have  not  only  this,  but  we  must  make  a  still  more  important  choice, 
namely,  that  of  the  locality  of  study.  To  make  this  selection  one  must 
possess  a  good  knowledge  of  animal  environments,  such  as  we  have 
touched  upon  in  the  preceding  pages. 

I.      BASIS   OF   SELECTION   AND   SUBDIVISION 

Such  knowledge  can  be  acquired  from  texts  of  physiography  and 
plant  ecology,  and  from  special  works  on  the  area  at  hand.     The  basis 


Fig.  8. — Map  showing  the  location  of  the  plains,  savanna  (prairie),  and  forest 
regions  of  North  America,  with  area  of  special  study  inclosed  in  rectangle  (from 
Transeau  after  Sargent). 

of  selection  is  either  that  of  age  or  of  present  conditions,  or  both.  The 
points  selected  for  study  are  called  stations.  Stations  are  subdivided 
on  the  basis  of  plant  and  animal  habitats  into  substations.  The  sub- 
stations may  represent  either  formations  or  divisions  of  formations. 
For  example,  a  station  like  Wolf  Lake  may  be  divided  into  sandy 
shore  substation,  vegetation  of  open-water  substation,  and  embayment 
substation. 

2.      ENUMERATION   OF   STATIONS — GUIDE 

In  the  study  at  hand  we  have  made  use  of  a  large  number  of  stations 
which  are  enumerated  below  and  are  referred  to  in  the  text.     The  list 


Z.  R  METCALF 

52  ANIMAL  ENVIRONMENT 

of  stations  and  accompanying  remarks  with  the  Guide  Map  may  serve 
as  a  guide  to  the  region  about  Chicago  for  field  students. 

List  of  Stations  with  Direction  and  Distance  by  Rail  from  the 
Mouth  of  the  Chicago  River,  and  Transportation 

A.    Aquatic  Communities 

I.    Large  Lake  Communities  (chap.  v). 

Station    i.    The  open  water,  piers  at  Jackson  Park,  6  miles  south. 

Station    la.  The  eroding  shore,  Jackson  Park,  introduced  rocks. 

Station  2.  The  eroding  shore,  Glencoe,  111.,  C.  &  N.W.  R.R.,  20  miles 
north. 

Station  3.  The  depositing  shore,  Buffington,  Ind.,  L.S.  &  M.S.  R.R., 
and  P.  R.R.,  22  miles  southeast.  Pine,  L.S.  &  M.S.  R.R., 
24  miles  southeast.    Boats  and  launch  from  fishermen. 

II.     Stream  Communities  (chap.  vi). 

Station    4.    Youngest  ravines,  Glencoe,  111.,  C.  &  N.W.  R.R.,  20  miles 

north. 
Station    5.    Youngest  brooks,  Glencoe,  111.,  C.  &  N.W.  R.R.,  20  miles 

north. 
Station    6.     County  Line  Creek,  Glencoe,  111.,  21  miles  north. 
Station    7.    Pettibone  Creek,  North  Chicago,  111.,  C.  &  N.W.  R.R., 

34  miles  north. 
Station    8.    Bull  Creek,  Beach,  111.,  C.  &  N.W.  R.R.,  41  miles  north. 
Station    9.     Dead  River,  Beach,  111.,  41  miles  north. 
Station  10.     Spring-fed  streams  and  springs,  Gary,  111.,  C.  &  N.W.  R.R., 

40  miles  northwest. 
Station  11.     Spring-fed  streams  and  springs,  Suman,  Ind.,  B.  &  O.  R.R., 

52  miles  southeast. 
Station  12.     Rock  ravine  stream,  the  Sag,  Joliet  Electric,    22   miles 

southwest. 
Station  13.    Intermittent  headwaters,  Butterfield  Creek,  Matteson,  111., 

I.e.  R.R.,  28  miles  south. 
Station  14.     Small  swift  permanent  stream,  Butterfield  Creek,  Floss- 
moor,  I.e.  R.R.,  24  mUes  south. 
Station  15.    Larger  swift  stream  and  effect  of  rock  outcrop,  Thornton, 

111.,  C.  &.  E.I.  R.R.,  23  mUes  south. 
Station  16.     Permanent  headwaters  and  pre-erosion  stream,  Hickory 

Creek,  Alpine  to  Marley,  Wabash  R.R.,  28  to  31  miles 

southwest. 
Station  17.     Permanent  swift  stream,  Hickory  Creek,  Marley  to  New 

Lenox,  Marley  (Wabash  R.R.  only).    New  Lenox,  C.R.I. 

&  P.  R.R.  or  Wabash  R.R.,  31  to  34  miles  southwest. 


INSERT  FOLDOUT  HERE 


LOCALITIES  STUDIED 


53 


Station  i8.     Sluggish  small  stream,  North  Branch  of  the  Chicago  River, 

Schermerville,  CM.  &  St. P.  R.R.,  21  miles  northwest. 
Station  19.     Moderately  swift,  medium-sized  stream,  North  Branch  of 

the  Chicago  River,  Edgebrook,  CM.  &  St.P.  R.R.,   12 

miles  northwest. 
Station  20.     Fine  gravel  bottom,  DuPage  River,  Winfield,  C  &  N.W. 

R.R.,  28  miles  west. 
Station  21.     Gravel  bottom,  DesPlaines  River,  Wheeling,  111.,  W.C  R.R., 

2,2,  miles  northwest. 
Station  22.     Sandy  bottomed  streams,  headwaters  of  the  Calumet,  Otis, 

Ind.,  L.S.  &  M.S.  R.R.,  50  miles  southeast. 
Station  23.    Larger  sandy   stream.  Little  Calumet,  Chesterton,  Ind., 

L.S.  &  M.S.  R.R.,  42  miles  southeast. 
Station  230.  Deep  river,  E.  Gary,  Ind.,  M.C  R.R.,  36  miles  southeast. 
Station  24.     Small  and  intermittent  sandy  streams,  South  Haven,  Mich. 

(4  miles  south),  steamer,  80  miles  northeast. 
Station  25.     Small    sandy    stream.    Deep    River   at    Ainsworth,    Ind., 

G.T.  R.R.,  46  miles  southeast. 
Station  26.    Medium  sandy  stream,  Black  River,  South  Haven,  Mich., 

steamer,  80  miles  northeast. 
Station  27.     Large  drowned  sandy  stream  with  marsh  border,   Deep 

River,  Liverpool,  Ind.,  P.  R.R.,  31  miles  southeast;  boats 

at  saloon. 
Station  28.     Sandy  large  drowned  stream.  Grand  Calumet,  Clark,  Ind., 

P.  R.R.  (destroyed  by  industrial  waste),    25  miles  south- 
east. 
Station  29.     Sluggish  stream  of  the  base-level  type.  Fox  River,  Cary, 

111.;  boats  near  railroad  bridge,  C  &  N.W.  R.R.,  40  miles 

northwest. 

III.    Small  Lake  Communities  (chap.  vii). 

Station  30.    Wolf  Lake  (a)  Roby,  Ind.,  L.S.  &  M.S.  R.R.,  P.  R.R., 
electric  railway  from  63d  St.,  and  Sheffield  boathouse,  15 
miles  southeast;  {b)  Hegewisch,  L.S.  &  M.S.  R.R.,  P.  R.R., 
or  South  Shore  Electric  R.R.,  boats  from  Delaware  House 
(not  practicable  at  low  water). 
Station  30(7.  Small  lake.  Lake  George,  Ind.     Electric  railway  from  Ham- 
mond or  to  Hammond  from  63d  St.,  or  from  Robertsdale, 
L.S.  &  M.S.  R.R.,  P.  R.R.,  18  miles  southeast;  boats  near 
south   end  of  lake.     For  information  regarding  Indiana 
lakes,  boats,  etc.,  see  Report  of  the  Indiana  Fish  and  Game 
Commission  for  1907. 
Station  31.     Fox  and  Pistakee  lakes.  Fox  Lake,  111.,  CM.  &  St.P.  R.R., 
50  miles  northwest;  boats  at  all  hotels. 


54 


ANIMAL  ENVIRONMENT 


IV.    Pond  Communities  (chap.  viii). 

Station  32.    Young  ponds,  Pond  i,  Buffington,  Ind.,    L.S.  &  M.S.  R.R. 

or  P.  R.R.,  22  miles  southeast  (i  miles  east  from  station). 
Station  S3-     Middle-aged  pond,  Pond  5,  Pine,  Ind.,  L.S.  &  M.S.  R.R., 

24  miles  southeast  (pond  at  rear  of  station). 
Station  34.     Middle-aged  pond,  Pond  7,  Pine,  Ind.,  L.S.  &  M.S.  R.R., 

24  miles  southeast  (pond  to  the  right  in  front  of  station). 
Station  35.     Mature   pond.    Pond    14,    Clark   Junction,  Ind.,  P.  R.R., 

23  miles  southeast  (the  fourth  pond  south  of  bridge  over 
P.  R.R.  tracks). 

Station  36.    Late  mature  pond,  Pond  30,  Clark,  Ind.,  P.  R.R.,  25  miles 

southeast  (pond  parallel  with  main  street  and  east  of  school) 
Station  37.     Senescent  pond,  Pond  52,  Cavanaugh,  Ind.,  South  Shore 

Electric  R.R.,  27  miles  southeast. 
Station  38.     Prairie  ponds,  Roby,  Ind.,  26  miles  southeast,  east  side  of 

Wolf  Lake,  between  second  and  third  icehouses. 
Station  39.     Morainic  pond  or  small  lake,  Butler's  Lake,  Libertyville,  111., 

CM.  &  St. P.  R.R.,  36  miles  northwest. 

B.     Temporary  Pond  and  Swamp  Communities. 

AQUATIC   PHASES    (CHAPS.    VIII  AND   x) 

Station  40.     Young  artificial  temporary  ponds.  Pine,  Ind.,  L.S.  &  M.S. 

R.R.,  24  miles  southeast  (ponds  i  mile  northwest  of  station). 

Station  41.     Middle-aged  temporary  ponds,  Pine,  Ind.,  L.S.  &  M.S.  R.R., 

24  miles  southeast  (ponds  i  mile  northeast  of  station). 
Station  42.     Prairie  temporary  ponds,  south  of  Jackson  Park,  I.C.  R.R.^ 

South  Chicago  Branch  to  Bryn  Mawr,  10  miles  south. 
Station  43.     Prairie  temporary  ponds,  8ist  St.  and  Stony  Island  Ave., 

electric  railway  from  63d  St.  and  Jackson  Park  Ave.,  south. 
Station  44.     Temporary  pond  of  prairie  type,  but  being  captured  by 

shrubs.  Pond  90  or  93,  Ivanhoe  Station,  L.S.  &  M.S.  R.R., 

to  Gibson,  Ind.,  and   G.  &  I.  R.R.   to  Ivanhoe   (i   mile 

south  of  Ivanhoe),  36  miles  southeast. 

C.    Marsh,  Forest  Margin,  and  Prairie  Communities 

Station  45.     Low  forest  margin  (see  Station  30). 

Station  46.     Intermediate  forest  margin,  Beverly  Hills,  C.R.I.  &  P.  R.R., 

12  miles  southwest. 
Station  47.     High    prairie,    Chicago    Lawn,    63d    St.    electric    railway, 

II  miles  southwest. 
Station  48.     High  prairie  (some  low  prairie).  Riverside,  111.,  C.B.  &  Q. 

R.R.  or  LaGrange  electric  railway,  12  miles  west. 
Station  49.     Temporary  forest   pond  of   early  stage,    Pond   93,   near 

Station  44. 


LOCALITIES  STUDIED 


55 


Station  50.     Strictly  temporary  forest  pond,  Pond  92,  near  Station  44. 

Station  51.  Spring-fed  marsh,  Gary,  111.,  C.  &  N.W.  R.R.,  40  miles 
northwest. 

Station  52.  Swamp  forest,  elm,  and  ash,  Wolf  Lake,  Roby,  Ind.,  south- 
east (same  as  Station  30). 

Station  53.  Swamp  forest,  wood  west  of  Dempster  St.,  Evanston,  111., 
C.  &  N.W.  R.R.,  elevated,  or  surface  cars,  12  miles  north. 

Station  54.  Tamarack  swamp,  Mineral  Springs,  Ind.,  South  Shore 
Electric  R.R,  46  miles  southeast.  (For  other  tamarack 
swamps,  see  map.) 

Station  540.  Tamarack  swamp,  Pistakee,  111.,  4  miles  south  of  Fox  Lake 
(see  Station  31). 

D.    Dry  Forest  Communities 

I.      EARLY   STAGES    (CHAP.    XH) 

Station  55.  On  rock,  Stony  Island,  L.S.  &  M.S.  R.R.,  12  miles  south 
on  suburban  loop.  Also  Pullman  electric  car  from  63d  St. 
and  Jackson  Park  Ave. 

n.      ON   CLAY    (chap.    XII) 

Station  56.     Bluff  at  Glencoe,  lU.,  C.  &  N.W.  R.R.,  20  mUes  north. 
Station  57.    On  sand,  moving  dunes.    Mineral  Springs,  Ind.  (near  Lake 

Mich,  and  Station  54). 
Station  58.    Lower    beach,    cottonwood   and   pine,    Pine,    Ind.    (near 

Station  40). 
Station  59.     Pine  and  oak,  Miller,  Ind.,  near  bridge  over  the  Calumet, 

L.S.  &  M.S.  R.R.,  31  miles  southeast. 
Station  60.     Black  oak  (same  as  Station  59  but  near  village). 
Station  61.     Clark,  Ind.,  near  Station  28. 
Station  62.     Cavanaugh,  Ind.,  near  Station  37. 
Station  63.     Black  oak,  white  oak,  red  oak,  near  Station  44. 


E.    Moist  Forest  Communities 

(chaps.  XI  AND  xn) 

Station  64.    White  oak,  red  oak,  hickory,  upland  forest,  near  Station  56. 
Station  65.     Forest  on  Blue  Island,  Beverly  Hills,  C.R.I.  &  P.  R.R., 

12  miles  southwest. 
Station  66.    Youngest  flood-plain  forest.  New  Lenox,  III,  C.R.L  &  P. 

R.R.,  also  Wabash  R.R.,  35  miles  southwest. 
Station  67.     Early  flood-plain  forest,  near  Station  15. 
Station  67a.  (Near  station  71a). 
Station  68.    Mature  flood-plain  forest,  near  Station  48. 


S6  ANIMAL  ENVIRONMENT 

Station  69.    Elm,  basswood,  oak,  hickory  forest,  Gaugars  (near  New 

Lenox),  37  miles  southwest,  Joliet  So.  Electric  R.R.  from 

Joliet  or  New  Lenox. 
Station  70.     Oak,  hickory,  beech,  maple,  Suman,  Ind.,  near  Station  11. 
Station  71.    Beech  and  maple,  Otis,  Ind.,  L.S.  &  M.S.  R.R.,  50  miles 

southeast. 
Station  71a.  Beech  and  maple,  Sawyer,  Mich.,  P.M.  R.R.,  73  miles 

east  (4  mUes  southwest). 
Station  yib.  Beech,  maple,  and  hemlock.  Sawyer,  Mich.,  P.M.  R.R., 

73  miles  east  (i|  miles  northwest). 

F.    Secondary  Communities 

Station  72.     Roadsides,  Flossmoor,  111.,  near  Station  14. 

Station  73.     South  Haven,  Mich,  (see  Station  24). 

Station  74.     Stream  contamination,  Riverdale,  111.,  I.C.  R.R.,  17  miles 

south. 
Station  75.     Pasturing  of  forests,  Beatrice,  Ind.,  C.C.  &  L.  R.R.,  45 

miles  southeast. 
Station  76.    The  growth  of  a  modern  city,  Gary,  Ind.;   many  lines  of 

transportation;  27  miles  southeast. 


VII.    Legal  Aspects  of  Field-Study 

The  student  must  recognize  that  legally,  when  he  leaves  the  public 
highway,  he  usually  becomes  a  trespasser,  even  though  he  walks  in  a 
stream  bed  or  along  a  lake  margin.  Public  property  is  scarce.  Still, 
since  the  cost  of  prosecution  is  far  greater  than  the  remuneration  secured 
by  it  in  the  way  of  damages,  etc.,  even  the  most  unreasonable  owners 
are  not  inclined  to  insist  upon  the  enforcement  of  the  laws  concerning 
trespassing.  It  should  be  borne  in  mind,  however,  that  owners  or 
tenants  are  entitled  to  respect,  and  that  as  a  usual  thing  they  will  not 
object  to  the  student's  working  on  their  property  if  they  be  treated  with 
courtesy.  Damaging  gates,  fences,  etc.,  should  be  carefully  avoided, 
and  gates  should  be  left  as  they  are   found. 

Small  wild  animals  such  as  insects,  snails,  etc.,  are  not  property, 
in  the  eyes  of  the  law,  and  an  owner  would  probably  not  be  able  to  pre- 
vent their  removal  from  his  land  except  by  trespass  procedure.  Many 
of  the  larger  animals  are  considered  as  public  property  and  are  therefore 
protected  by  law.  In  most  states  nearly  all  birds  are  protected  by  law. 
It  is  usually  legal  to  kill  certain  game  birds  in  season,  and  certain  con- 
demned birds  at  all  times.  Game  mammals  are  protected  in  accordance 
with  a  similar  plan.     It  is  usually  necessary  that  a  license  to  shoot  be 


LEGAL  ASPECTS 


57 


obtained  before  shooting  of  any  sort  be  carried  on.  This  would  apply 
even  to  the  shooting  of  snakes,  lizards,  and  such  animals,  as  well  as 
game. 

Fishes,  turtles,  and  fresh-water  mussels  are  protected  in  Illinois, 
as  are  fishes  in  nearly  all  states.  The  use  of  seines  and  nets  of  all  sorts, 
including  hand  dip-nets,  dynamite,  and  all  other  devices  for  securing 
fishes,  is  usually  forbidden.  The  hook  and  line  is  the  only  exception 
in  some  states.  Forbidden  equipment  is  nearly  always  confiscatable, 
and  the  fines  for  illegal  fishing  are  usually  very  heavy. 

In  some  states  it  is  possible  to  obtain  licenses  or  permits  to  take 
birds,  birds'  eggs,  and  sometimes  fishes  for  scientific  purposes.  For 
specific  information  one  should  consult  the  state  fish  and  game  warden. 


CHAPTER  IV 

CONDITIONS  OF  EXISTENCE  OF  AQUATIC  ANIMALS 
I.    Introduction:  Comparison  of  Land  and  Aquatic  Animals 

The  conditions  of  existence  of  aquatic  plants  and  animals  are  very 
different  from  those  of  land  plants  and  animals.  Some  of  the  most 
important  diflferences  are  as  follows: 

a)  Water,  the  surrounding  medium,  is  about  768  times  as  heavy 
as  atmospheric  air  at  the  sea-level. 

6)  The  necessary  gases  are  in  solution  in  the  water  and  their  diffusion 
is  much  less  rapid  than  in  the  atmosphere. 

c)  The  necessary  inorganic  salts  are  in  solution  in  the  surrounding 
medium. 

d)  The  necessary  organic  food  substances  for  plants  and  some  of  the 
carbon  compounds  necessary  for  animals  are  in  solution  in  the  water  and 
are  taken  directly  by  the  plants  and  animals  (47). 

e)  Vegetation  rooted  to  the  bottom  is  important  in  most  bodies  of 
water.  In  large  lakes  like  Lake  Michigan,  however,  there  are  very  few 
attached  or  rooted  plants,  and  therefore  nothing  comparable  to  the 
vegetation  of  the  land,  or  to  the  plant-eating  animals  which  live  on  it, 
is  to  be  found.  Most  of  the  plants  float  freely  in  the  water.  Such 
plants  are  present  also,  however,  where  rooted  vegetation  occurs. 

II.    Chemical  Conditions 

I.      DISSOLVED  content   OF  WATER 

In  order  to  support  animals  and  plants,  water  must  contain  certain 
minerals  and  gases  in  solution  (71).  Salts  (carbonates,  sulphates,  and 
chlorides)  of  magnesium,  calcium,  and  sodium  and  salts  of  potassium, 
iron,  and  silicon  are  practically  always  present  in  solution  in  water,  and 
their  presence  in  definite  proportions  is  essential  to  the  life  of  the  animals 
(72).  Water  without  these  has  been  shown  to  kill  fish  (71).  Dissolved 
gases  in  definite  proportions  are  also  necessary. 

Gases. — The  chief  facts  regarding  the  occurrence  of  gases  in  nature 
and  their  solubility  under  experimental  conditions  are  shown  in  Table  II. 
The  standard  method  of  expressing  quantity  of  gas  in  solution  is  in  cubic 
centimeters  per  liter  at  0°  C.  and  760  mm.  of  mercury  (73).  All  values 
are  therefore  given  in  these  terms. 

58 


CHEMICAL  CONDITIONS 

*  TABLE  II 

Showing  the  Distribution  and  Solubility  of  Atmospheric  Gases 


59 


Gas  Values  in 

Cubic  Centimeters  per  Liter 

AT  0°   C 

AND  760  MM.  Mercury 

CoMPosmoN 

Kind  of  Water 

Having  Gas 

Gas 

OF  Air  in 

At  Temperature 

20°  C.  760  mm. 

Maximum 

Content  Given 

Percentages 

Amounts  Found 
in  Natural   Fish 

in  Preceding 

Column 

Water  Absorbs 

Water  Absorbs 

Waters,    Springs 

from  Air 

Pure  Gas 

Excepted 

Nitrogen, 

argon,  etc. . 

79.02 

12.32  c.c. 

15.00  C.C. 

19.00  C.C. 

Lakes  (74, 
P-  152) 

Oxygen 

20.9s 

6.28  C.C. 

28.38  C.C. 

24.00  C.C. 

Streams, 
lakes,  win- 
ter, with 
green 
algae 

Carbon 

dioxide.  .  .  . 

0.03 

0.27  C.C. 

901. 00  C.C. 

30.00  C.C. 

Ponds 

Ammonia.  .  .  . 

Small  traces 

Very  large 

14.00  C.C. 

Sewage  con- 

locally 

quantities 

taminated 

Methane 

Small  traces 
locally 

34.00  C.C. 

10.00  C.C. 

Bottom  of 
lake  in 
September 
(74,p.ioi) 

Nitrogen  has  little  effect  upon  animals  e.xcept  when  present  in  excess. 
Under  these  conditions  in  the  laboratory,  bubbles  of  the  gas  accumulate 
in  the  tissues  and  blood-vessels  of  fishes  and  cause  death.  It  is  not 
certain  that  such  conditions  exist  in  nature  (Fig.  9). 

Oxygen  is  usually  necessary  to  the  life  of  animals.  Most  animals 
that  have  been  studied  select  water  with  a  rather  high  oxygen  content 
instead  of  water  with  little  or  no  oxygen.  The  resistance  of  animals  to 
lack  of  oxygen  varies  in  different  groups.  It  has  been  found  that  water 
with  about  6  c.c.  of  oxygen  and  14  c.c.  of  nitrogen  per  liter  is  suitable 
for  brook  trout.  Mackinaw  trout  have  been  taken  in  water  containing 
but  I  c.c.  of  oxygen  per  liter  (6). 

In  general,  carbon  dioxide  is  a  narcotic  in  its  action  upon  animals. 
In  small  quantities  it  is  a  stimulant,  especially  to  respiratory  action. 
In  large  quantities  it  produces  anesthesia  and  death.  Several  workers 
have  shown  that  carbon  dioxide  is  very  toxic  to  fishes.  Most  aquatic 
animals  that  have  been  studied  turn  back  when  they  encounter  water 
containing  large  amounts  of  the  gas.  This  turning  away  from  carbon 
dioxide  is  much  more  decided  than  it  is  in  the  case  of  corresponding 
differences  (24  c.c.  per  liter)  in  oxygen  content.     Fishes,  for  example, 


6o 


AQUATIC  CONDITIONS 


turn  away  when  they  encounter  as  small  an  increase  as  5  c.c.  per  liter 
of  carbon  dioxide.  Since  a  large  amount  of  dissolved  carbon  dioxide 
is  commonly  accompanied  by  a  low  oxygen  content  as  well  as  other 
important  factors,  the  carbon  dioxide  content  of  water  (strongly  alkaline 
waters  excepted)  is  probably  the  best  single  index  of  the  suitability  of 
the  water  for  fishes. 

Fishes  do  not  turn  away  from  ammonia.     Ammonia  is  rarely  present 
in  any  great  amount  in  nature.     The  effect  of  dissolved  methane  is 

unknown.  Oxygen  and  nitrogen  go  into  solu- 
tion from  the  atmosphere  and  oxygen  is  also 
produced  by  green  plants.  The  other  gases 
are  produced  chiefly  by  organisms  as  excretory 
and  decomposition  products. 

III.    Physical  Conditions 

I.      CIRCULATION 

The  distribution  of  dissolved  salts  and 
gases  is  dependent  upon  the  circulation  of  the 
water,  as  their  diffusion  is  too  slow  to  keep 
them  evenly  distributed.  The  circulation  of 
water  in  streams  is  probably  such  as  to  keep 
all  dissolved  gases  and  salts  about  equally 
distributed.  The  water  of  streams  has  been 
found  to  be  supersaturated  with  oxygen  (74). 
Oxygen  is  taken  up  by  the  water  near  the 
surface.  Nitrogen  and  carbon  dioxide  are 
produced  especially  near  the  bottom,  and  if 
the  water  did  not  circulate  they  would  be  too 
abundant  in  some  places  and  deficient  in 
others  for  animals  to  live. 

In  lakes,  during  strong  winds  (74),  there  is 
a  piling-up  of  water  on  the  leeward  side  and  a 
lowering  of  the  level  on  the  windward  side.  This  is  usually  com- 
pensated for  by  a  downward  flow  of  the  waters  along  the  bottom, 
as  shown  in  Fig.  10.  Small  lakes  with  little  exposure  to  the  wind 
and  with  considerable  depth  frequently  develop  a  summer  circulation, 
such  as  is  shown  in  Fig.  11.  Such  lakes  are  without  oxygen  in  the 
deeper  water  in  summer  (74),  and  will  not  support  the  fishes  which  are 
known  to  inhabit  the  deeper  water  of  Lake  Michigan;  hence  we  con- 
clude that  Lake  Michigan  must  have  a  deep  circulation  at  all  times. 


Fig.  9. — A  marine  fish 
affected  with  gas-bubble 
disease  causing  protrusion 
of  the  eyes,  due  to  excess 
of  dissolved  nitrogen  in 
aquarium  water  (after  Gor- 
ham). 


CIRCULATION  AND  TEMPERATURE 


6l 


We  have  been  able  to  find  no  record  of  the  amount  of  lowering  of 
the  waters  of  Lake  Michigan  at  a  given  point,  by  the  wind,  nor  any 
discussion  of  the  relations  of  the  surface  currents  to  the  effects  of  winds 
and  the  vertical  circulation.  The  waves  of  large  lakes  rise  to  consider- 
able heights,  as  is  familiar  to  all.  They  are  of  much  importance  in 
keeping  a  large  amount  of  gas  in  solution  in  the  lake  waters. 

The  current  in  streams  differs  from  that  in  lakes  in  that  it  is  for  the 
most  part  in  one  definite  direction,  while  the  lake  currents  often  alternate. 
There  are  backward  flows  and  eddies  at  various  points  in  streams,  in 
front  of  and  behind  every  object  encountered  in  the  current  (57,  p.  124). 
On  the  basis  of  the  current,  streams  are  classified  as  intermittent,  swift, 


Fig.  10. — Showing  the  circulation  of  the  water  in  a  lake  of  equal  temperature. 
W  represents  the  direction  of  the  wind  (after  Birge). 

Fig.  II. — ^The  circulation  of  the  waters  of  a  lake  of  unequal  temperature  (after 
Birge). 

moderately  swift,  sluggish,  and  stagnant  or  ponded.  The  current 
within  the  same  stream  differs  at  different  times,  and  in  different  places. 
As  we  pass  across  a  stream  w^e  find  the  current  swiftest  near  the  surface 
in  the  middle,  and  least  swift  at  the  bottom  near  the  sides. 

2.      TEMPERATURE 

Temperature  has  always  been  regarded  as  of  great  importance  in 
the  direct  control  of  the  distribution  of  life  in  water.  The  tendency  of 
modern  investigation  is  to  show  that  its  influence  is  of  great  indirect 
importance,  and  the  belief  in  its  direct  importance  is  correspondingly 
weakened. 

The  temperature  in  a  stream  is  probably  about  the  same  at  the 
various  points  in  any  cross-section.  The  extent  to  which  daily,  seasonal, 
and  weather  fluctuations  in  atmospheric  temperature  affect  a  lake  is 


62 


AQUATIC  CONDITIONS 


determined  by  the  depth.  Small  lakes  with  incomplete  circulation  in 
summer  are  cold  at  the  bottom,  being  heated  at  the  surface  only  (Fig.  ii). 
Lake  Michigan  is  a  deep  lake  and  none  of  these  fluctuations  is  felt 
throughout  (see  Table  III  below  and  Table  IX,  p.  74).  In  summer  the 
water  of  the  surface  is  warmed,  but  if  the  vertical  circulation  is  what 
we  suppose  it  to  be,  all  the  heat  in  the  waters  flowing  downward  at  the 
leeward  side  (Fig.  10)  must  be  absorbed  above  no  meters.  Table  III 
shows  the  temperatures  recorded  by  Ward  (75);  these  were  evidently 
taken  at  the  bottom  and  do  not  therefore  represent  the  temperatures 
at  the  same  level  in  the  open  water,  especially  those  records  made  in 
the  shallower  situations  where  the  sun's  rays  can  reach  the  bottom 
essentially  undiminished  in  intensity. 

TABLE  III 
Temperature  of  Lake  Michigan 


Hour  P.M. 

Tempera- 

Tempera- 

Temperature at 

Date 

Unless 

Sky 

ture  of 

ture  at 

Depth  in 

Depth 

Stated 

Air 

Surface 

Next  Column 

Meters 

Feet 

Aug.  16 

4:0s 

Clear 

16. 7° c. 

18.3° c. 

18.3° c. 

64.9°  F. 

5-66 

18.6 

Aug.  18 

9:00  A.M. 

Cloudy 

18.9° c. 

17. 2°  C. 

16. 7°  C. 

62.0°  F. 

11.32 

37-1 

Aug.  18 

12:25 

Clear- 
ing 

16. 7° C. 

17. 5°  C. 

7.2°C. 

44.9° F. 

22.63 

74.1 

Aug.  16 

S:io 

Clear 

16. 7° C. 

18.3° c. 

7.5°C. 

45.5°F. 

32.06 

105.2 

Aug.  25 

3:2s 

20.0° C. 

i9.4°C. 

7.2°C. 

44.9°  F. 

43.38 

142.3 

Aug.  16 

12:05 

Clear 

iS.6°C. 

18.3° C. 

5.2°C. 

41.3°  F. 

55-93 

183.5 

Aug.  II 

10:30  A.M. 

Hazy 

18.9° C. 

s.i°c. 

41 . 1°  F. 

108. 22 

355-0 

Aug.  16 

1:50 

Clear 

16. 7'' C. 

18.3° C. 

4.2°C. 

39.5° F. 

1 1 2 . 00 

367.5 

Aug.  18 

4:30 

Scat- 
tered 
clouds 

18.9°  C. 

18.3° c. 

4.2°C. 

39.5°F. 

132.66 

436.0 

3.      LIGHT    (76) 

•Light  is  an  important  factor  in  controlling  the  distribution  and 
activities  of  animals.  The  depth  to  which  light  penetrates  water  is 
therefore  of  importance.  Forel  found  that  in  Lake  Geneva,  Switzer- 
land, during  the  period  when  the  water  was  clearest,  light  diminished 
gradually  from  25  to  65  meters,  and  then  decreased  rapidly  to  115  meters 
where  there  was  not  sufiicient  light  to  affect  the  photographic  plate. 
No  doubt  future  investigation  with  more  accurate  means  of  measuring 
light  will  show  that  very  faint  light  penetrates  much  farther.  The 
depth  of  light  penetration  in  fresh  water  is  usually  determined  by  the 
amount  of  sediment  in  the  water.  Forel  found  that  in  Lake  Geneva 
the  depth  of  light  penetration  decreased  with  the  melting  of  the  mountain 


LIGHT  AND  PRESSURE 


63 


snows  and  the  beginning  of  the  rainy  season.  The  drainage  area  of  Lake 
Michigan  is  very  small  and  has  little  relief,  and  the  amount  of  sediment 
carried  in  is  small  at  all  times.  The  depth  of  light  penetration  is  there- 
fore not  so  much  influenced  by  these  factors  as  in  Lake  Geneva.  Wave- 
action  is  also  important  in  stirring  the  bottom  materials  near  shore. 
We  would  expect  the  light  penetration  in  Lake  Michigan  to  be  least 
during  the  rainy  and  windy  seasons,  and  greatest  in  calm,  dry  weather — 
late  summer  and  autumn.^  All  of  the  surrounding  physiographic  con- 
ditions are  factors  controlling  light.  Table  IV  shows  the  seasonal 
distribution  of  rainfall  and  light  penetration  in  Lake  Geneva,  and  the 
seasonal  distribution  of  winds  and  rainfall  at  Chicago. 

TABLE  IV 

Showing  Depth  of  Light  Penetration  in  Lake  Geneva  and  Conditions  Affect- 
ing THE  Same  in  Both  Lake  Geneva,  after  Forel  (76,  Vol.  11, 
p.  439),  AND  Lake  Michigan 
In  the  eighth  column  the  results  are  given  in  seconds,  in  terms  of  the  effect  on  the 
photographic  plate,  of  equivalent  exposures  to  the  sun. 


Month 


Lake  Michigan 


Lake  Geneva,  Switzerland  (after  Forel) 


Rainfall 


Inches 


January..  . 
February. . 
March.  .  . 

April 

May 

June 

July 

August. . .  . 
September 
October.  .  . 
November. 
December . 


2.0 

2-3 

2-5 

2-7 

3-5 
3-7 
3-6 
2.8 
30 
2.6 
2.6 
2. 1 


Centi- 
meters 


'''"^l^ir"'*    !     Rainfall  and  Light 


Miles  per 
Hour 


5-2 

6.4 
6.9 
8.9 

9.4 
9.2 

7-2 

7-7 
6.6 
6.6 
5-3 


17.8 
20.0 
20.4 
19.4 
18.3 

14.4 
14.6 

134 
16.  7 
17.6 
19.0 
19.9 


Meters 

per 
Second 


Prec.  in 
Cm. 


Light 
Limit  at 
Depth  in 

Meters 


Light  and  Depth 


Intensity 
of  Light 
(March) 
at  Depth 
in  Next 
Column 


500  sec. 
500  sec. 
500  sec. 
400  sec. 
360  sec. 
120  sec. 

60  sec. 

25  sec. 

10  sec. 
2  sec. 
o  sec. 


Depth  in 
Meters 


19.6 
25.  2 

45 -S 
5S-S 
65.6 
75-6 
85.7 
95-8 
105-4 
115. 6 


4.      PRESSURE    (76) 

Pressure  in  w^ater  increases  with  depth.     The  results  given  by  Forel 
are  shown  in  Table  V. 

'The   Lake  Michigan  Water  Commission  has   reported   greatest   turbidity  in 
January,  February,  March,  and  April. 


64 


AQUATIC  CONDITIONS 
TABLE  V  (76) 


Pressure  in 
Atmospheres 

I 

2 

3 

5 

8 

10 

20 

Depth  in  meters. 

10.328 

20.6 

30.9 

Si-5 

82.4 

103.27 

206 . 49 

It  will  be  noted  that  there  is  a  little  more  than  one  atmosphere 
increase  in  pressure  for  each  10  meters  (33  feet)  in  depth  because  water 
is  very  slightly  compressible.  According  to  this,  animals  in  the  deepest 
parts  of  Lake  Michigan  are  living  under  a  pressure  of  about  375  pounds 
to  the  square  inch. 

5.      BOTTOM 

The  character  of  materials  and  topography  of  the  bottom  are  very 
important  to  animals  living  on  the  bottom,  but  it  has  its  effect  also  on 
free  swimming  animals  as  a  determining  factor  in  the  amount  of  sedi- 
ment. 

The  kind  of  bottom  is  important  because  many  animals  are 
dependent  upon  solid  objects  for  attachment  and  are  absent  from 
bottoms  made  up  of  fine  materials.  Others  must  burrow  into  mud 
or  creep  on  sand  and  gravel.  This  will  be  discussed  later  in  special 
cases,  particularly  in  streams. 

Topography  of  the  bottom  in  shallow  water  is  important  in  lakes 
locally  in  affecting  wave-action  and  currents,  and  through  these,  bottom 
vegetation  and  temperature.  Ward  (75)  noted  such  effects  but  did 
not  carry  the  work  far  enough  to  solve  any  of  the  problems  involved, 
which  are  usually  local.  In  lakes,  bottom  materials  are  most  important 
in  shallow  water,  because  of  their  effect  in  connection  with  wave-action, 
the  amount  of  sediment  in  suspension,  and  the  stability  of  the  bottom. 
The  bottom  materials  of  lakes  vary  greatly  locally.  Taking  Lake 
Michigan  as  an  example,  if  we  were  to  see  the  region  about  Chicago 
denuded  of  all  vegetation,  we  would  be  able  to  appreciate  the  fact  that 
there  are  bowlder  deposits,  gravel  deposits,  sand,  clay,  and  bare  rock. 
Evidently  the  ice  sheet  left  the  same  kind  of  bottom  materials  strewn 
with  the  same  irregularity  in  the  bottom  of  the  lake  as  on  the  land. 
Apparently  wave-action  has  not  affected  them  below  25  meters  (85  feet). 
The  waves  of  Lake  Michigan  are  believed  not  to  move  sand  below 
9  meters  (30  feet).  It  is  thought  that,  during  the  Champlain  stage,  the 
lake  stood  at  a  level  60  feet  below  its  present  level.  Along  the  north 
shore  there  is  a  cliff  at  this  level  with  sand  deposits  lying  on  the  side 
toward  the  deeper  water.     Inside  of  this  is  an  area  of  clay  and  then,  next 


VEGETATION  AND  FOOD  SUBSTANCES  65 

to  the  present  shore,  sand  and  gravel  again.  It  is  seen  that  this  lower 
level  of  the  lake  influenced  both  the  topography  and  bottom  material 
locally,  both  of  which  probably  have  an  influence  on  the  occurrence  of 
certain  animals. 

6.      VEGETATION 

^  The  amount  and  kind  of  rooted  vegetation  is  very  important  to 
animals.  Of  all  the  aquatic  situations  with  which  we  have  to  deal 
Lake  Michigan  has  fewest  attached  plants,  and  these  are  all  algae. 
Cladophora,  Chara,  and  filamentous  algae  are  the  most  important. 
These  do  not  appear  to  have  been  recorded  below  about  25  meters; 
some  of  them  require  solid  bodies  for  attachment,  and  are  probably  most 
abundant  on  the  rock  outcrops  of  shallow  water. 

The  vegetation  of  the  younger  streams  consists  largely  of  holdfast 
algae  like  those  along  the  rock  shores  of  the  lake.  These  are  of  impor- 
tance to  animals.  The  more  sluggish  streams  have  rooted  aquatic 
\'egetation. 

The  vegetation  is  used  as  breeding-places.  Eggs  are  stuck  into  plant 
tissues  by  the  predaceous  diving  beetles  {Dytiscidae)  and  by  the  water 
scorpions  {Ranatra).  Eggs  are  attached  to  plants  by  the  electric-light 
bugs  {Belostomidae) ,  back-swimmers,  May-flies, '  caddis-flies,  water 
scavengers  (Hydrophilidae),  long-horned  leaf  beetles  {Donacia),  snails, 
and  many  fish  {Umbra,  and  probably  Abramis).  Young  animals  are 
often  dependent  upon  plants  for  shelter,  to  escape  from  enemies,  etc. 
Many  animals  must  use  plants  as  a  means  of  reaching  the  surface  for 
oxygen.  The  most  important  of  these  are  the  Dytiscidae  (adults  and  lar- 
vae), the  Hydrophilidae  (adults  and  larvae),  the  back-swimmers,  Zaitha, 
Belostoma,  Donacia,  snails,  Ranatra,  and  Haliplidae.  Some,  for  example 
Zaitha  and  dragon-fly  nymphs,  lie  in  the  vegetation  and  wait  for  their  prey. 

Different  kinds  of  vegetation  have  different  values  for  animals. 
The  bulrush  is  barren  for  the  following  reasons:  (i)  hardness  makes  it  a 
bad  place  for  eggs;  (2)  there  are  no  clinging-places ;  (3)  there  is  little 
shade;  (4)  it  gives  a  high  temperature  in  summer;  (5)  there  is  no  great 
addition  of  oxygen  by  vegetation;  (6)  it  does  not  afford  a  suitable  place 
for  securing  food.  Equisetum  is  unfavorable  for  similar  reasons.  Elodea 
is  excellent;  Myriophyllum,  good;  water-lilies  and  Chara,  only  fair. 

IV.     Elementary  Food  Substances  (47) 
Nitrogen,  in  the  form  of  nitrates,  is  necessary  for  the  growth  of  the 
plants  of  a  pond,  lake,  or  stream,  and  an  insuflScient  quantity  is  secured 
from  mineral  soil.     Nitrogen  can  be  taken  from  the  air  only  by  nitrogen- 


66  AQUATIC  CONDITIONS 

fixing  bacteria,  such  as  Azotobacter,  an  aerobe,  and  Clostridium,  an 
anaerobe.  These  bacteria  occur  on  the  outside  of  plants  and  animals, 
in  the  mud  of  the  bottom,  etc.  Plants  and  animals  provide  carbon  for 
the  bacteria ;  bacteria  provide  the  nitrites  or  nitrates  for  the  plants. 

Ammonia,  resulting  from  the  decomposition  of  proteid  of  the  dead 
bodies  of  plants  and  animals,  is  oxidized  to  nitrous  acid;  nitrous  acid  is 
oxidized  to  nitric  acid  by  the  bacteria  {Nitrosomonas,  Nitrobader,  Nitro- 
coccus).  This  acid  unites  with  bases  to  form  nitrates  and  nitrites. 
There  are  accordingly  two  sources  of  nitrate  and  nitrite.  Working 
against  these  are  the  denitrifying  bacteria  {Bacterium  actinopelte  [Baur]) 
which  reduce  nitrogen  compounds  to  free  nitrogen.  Their  work  is 
influenced  by  temperature.  Baur  placed  a  standard  quantity  of  nitrate 
infected  with  Bacterium  actinopelte  at  several  temperatures  (47,  p.  271) 
with  results  as  follows: 

1.  Temperature  25°  C:  Denitrification  began  24  hours  after  inocu- 
lation; in  7  to  II  days  later  the  solution  was  nitrate-free. 

2.  Temperature  15°  C:  Denitrification  began  4  days  after  inoculation; 
in  27  days  the  solution  was  nitrate-free. 

3.  Temperature  4-5°  C:  Denitrification  began  20  days  after  inocula- 
tion;  process  incomplete  112  days  after. 

4.  Temperature  0°  C. :    Denitrification  not  initiated. 

The  quantity  of  life  in  water  has  been  held  by  some  to  be  in  propor- 
tion to  the  available  nitrogen.  The  amount  of  plankton  in  the  sea  is 
greatest  in  the  polar  regions  in  summer.  It  has  been  suggested  that 
the  greater  retarding  effect  of  low  temperature  on  the  denitrifiers,  as 
compared  with  the  producers  of  nitrates,  is  a  cause  of  the  greater  quantity 
of  Ufe  in  colder  waters.  Atmospheric  nitrogen  in  solution  is  important 
in  the  building  of  nitrogen  compounds  by  nitrogen-fixing  bacteria. 
Oxygen  is  necessary  for  the  life  of  most  organisms,  though  a  few  can 
live  for  considerable  periods  in  its  absence.  Carbon  dioxide  is  necessary 
for  starch  building  by  chlorophyll-containing  plants  and  animals. 
These  organisms  form  the  principal  (food)  basis  of  all  other  organisms. 

Complex  foodstuffs,  such  as  proteids,  are  necessary  for  most  animals. 
It  is  only  animals  which  contain  chlorophyll  in  the  form  of  algae  living 
symbiotically  in  their  bodies,  or  otherwise,  that  can  live  without  taking 
in  proteid  from  the  outside.  Proteids  are  made  only  when  light  for  the 
production  of  starch,  nitrates,  and  several  other  inorganic  foods  are 
present.  Light  is  then  indirectly  necessary  to  animals  which  can  live 
in  darkness. 

The  smaller  aquatic  animals  are  commonly  either  alga-eaters  or 
predatory.     The  larger  aquatic  animals  are  commonly  predatory  or 


QUANTITY  67 

scavengers.  The  rooted  vegetation  is  eaten  only  to  a  small  extent. 
Small  floating  or  swimming  plants  and  animals,  called  plankton  (Figs. 
12-18,  pp.  75,  76)  are  the  basis  of  the  food  supply  of  larger  animals. 
We  could  probably  remove  all  the  larger  rooted  plants  and  substitute 
something  else  of  the  same  form  and  texture  without  greatly  affecting 
the  conditions  of  life  in  the  water,  that  is,  so  far  as  the  life  habits  of  the 
animals  are  concerned.  The  aquatic  plants  are  commonly  covered  with 
a  coating  of  green  algae,  protozoa,  and  other  small  organisms,  so  that 
animals  such  as  small  snails  may  rasp  the  surface  of  the  plants  and  secure 
food  without  eating  the  plant  tissues  themselves.  Plants  in  water  are 
of  particular  use  to  animals  as  clinging-  and  nesting-places. 

V.    Quantity  (47)  of  Life  in  Water 

The  quantity  of  living  matter  in  water,  so  far  as  it  is  plankton  or 
floating  organisms,  has  been  much  studied.  The  quantity  is  usually 
expressed  in  one  of  two  ways:  number  of  organisms  per  liter  or  cubic 
meter  of  water,  determined  by  counting  a  part  of  a  collection;  or  in 
cubic  centimeters  per  cubic  meter  of  water.  In  Lake  Michigan  (August) 
Ward  (75)  found  an  average  of  11 . 5  c.c.  per  cubic  meter  in  water  from 
the  surface  to  2  m.;  from  2-25  m.,  3.9  c.c;  25  m.  to  bottom,  o.  4-1 . 5  c.c. 
He  found  that  Pine  Lake  (a  small  lake)  contained  relatively  less  plankton 
than  Lake  Michigan,  the  surface  stratum  of  Pine  Lake  containing  more 
and  the  deeper  strata  much  less  than  the  larger  lake.  Lake  St.  Clair 
contains  only  one-half  as  much  plankton  as  Lake  Michigan.  Lake 
Michigan  contains  only  about  one-tenth  as  much  plankton  as  some  of  the 
small  European  lakes  (Dobersdorfer  See).  Kofoid  (77)  found  71 .36  c.c. 
per  cubic  meter  the  maximum  record  for  the  Illinois  River.  The 
average  for  the  year  is  2.71  c.c.  per  cubic  meter.  The  largest  amount 
recorded  by  Kofoid  is  684.0  c.c.  per  cubic  meter  (Turkey  Lake,  Ind.)  . 

Small  streams  and  lakes  with  large  inflow  and  outflow  have  but  little 
plankton.  Large  amount  of  plankton  is  commonly  associated  with 
high  CO2  content,  low  oxygen  content,  and  a  large  amount  of  carbonate 
in  solution. 

The  amount  fluctuates  from  season  to  season.  Kofoid  (77)  found 
the  maximum  for  the  Illinois  River  in  April  to  June.  The  amount 
gradually  decreases  until  December  and  January,  when  the  minimum 
is  reached.  He  also  found  evidence  that  the  light  of  the  moon  increases 
photosjoithesis  and  the  amount  of  plankton.  The  maximum  of  Crustacea 
was  found  by  Marsh  (78)  to  fall  in  July,  August,  and  September,  differing 
in  different  years.     The  maximum  in  Lake  Michigan  probably  is  usually 


68 


AQUATIC  CONDITIONS 


in  late  summer  or  early  autumn.     Smaller  bodies  of  water  are  similar 
in  this  respect. 

I.      LAW   GOVERNING   QUANTITY    (47) 

Liebig's  Law  of  Minimum,  as  applied  to  plants,  is  stated  as  follows: 
"A  plant  requires  a  certain  number  of  foodstuffs  if  it  is  to  continue  to 
live  and  grow,  and  each  of  these  food  substances  must  be  present  in  a 
certain  proportion.  If  one  of  them  is  absent,  the  plant  will  die;  if  one 
is  present  in  a  minimal  proportion,  the  growth  will  also  be  minimal. 
This  will  be  the  case  no  matter  how  abundant  the  other  foodstuffs  may 
be.  Thus  the  growth  of  a  plant  is  dependent  upon  the  amount  of  the 
foodstuff  which  is  presented  to  it  in  minimal  quantity"  (47,  p.  234). 
The  amount  of  plankton  is  determined  by  the  same  law.  All  food  sub- 
stances must  be  present  in  the  correct  proportions.  The  amount  of 
plankton  may  be  determined  by  one  substance  which  is  deficient  in 
amount. 

2.     AGE  AND  QUANTITY  (6  and  citations) 

In  bodies  of  water  with  small  outlet,  the  quantity  of  plant  and  animal 
life  probably  increases  with  the  age  of  the  water  body.  This  is  because 
the  foodstuffs  are  washed  in  by  the  inflowing  water,  and  because  rooted 
plants  absorb  food  from  the  soil  in  which  they  grow,  and  when  they  die 
and  decay  these  foodstuffs  are  added  to  the  water.  Accordingly,  the 
older  the  pond  and  the  longer  rooted  vegetation  has  grown,  the  greater 
the  quantity  of  life.  This  principle  is  illustrated  by  an  age-series  of 
ponds  at  the  south  end  of  Lake  Michigan  to  be  discussed  in  detail  later. 
The  numbers  used  indicate  relative  age.  Ponds  i,  5,  7,  14,  30,  52,  89, 
and  95  were  studied,  but  especially  i,  5,  7,  and  14  (6).  Tables  VI-VIII 
give  a  summary  of  the  results. 

TABLE  VI 

Showing  Quantitative  Results  of  Examination  of  Factors  Related  to 
Quantity  or  Plankton 


Pond  Numbers — Age-Series 


No.  of 
Collection 


Total  carbonates  in  parts  per  million  .  . 

CO2,  c.c.  per  liter* 

Oxygen,  c.c.  per  liter* 

Bacteria  per  c.c 


138.800 
0.0 
6.28 
779 


160. 200 
3-4 
3-47 
2450 


160.300 

2.7 
2.78 

3550 


•Average  of  collections,  April,  May,  June,  July,  taken  over  sandy  bottom  (pond  i)  or  at  the  top 
of  submerged  vegetation  (ponds  7  and  14). 


QUANTITY 


69 


We  note  that  on  the  whole  the  carbonates,  CO2,  and  bacteria  are 
greater  in  quantity  according  to  age.    Oxygen  is  on  the  whole  less. 

TABLE  VII 
Showing  the  Number  of  Entomoslraca  in  Approximately  90  Liters  of  Water 


Body  of  Water 

September  3,  4 

April  30,  1910 

Average  of 
Collections  in 
Parentheses 

Relative  Age 

Wolf  Lake 

213 

232 

4,115 

556 

539 

2,773 

2,900 

9,333 
19,866 
Aug.  28,  191 2 
104 

1,556   (3) 

4,781   (3) 

11,991   (3) 

874  (6) 

927  (6) 

2,680  (6) 

1 
2 

Prairie  Pond  I 

3 

Prairie  Pond  II 

Pond  I    

14 
I 

Pond  7 

7 

Pond  14 

14 

Pond  30 

1,039                    

351                    2,600 

2,870      !       11,400 
....       1        2,480 

30 

Pond  52 

52 

Pond  89 

89 

Pond  0  ? 

95 

TABLE  VIII 

Showing  Ratio  of  Number  or  Quantity  of  Different  Organisms  When  the 

Maximum  Is  ioo 


Rooted  vegetation 
Entomostraca .... 
Midge  larvae .... 

Sphaeridae 

Gilled  snails 

Lunged  snails .  .  .  . 

A  niphipoda 

Crayfishes 

Insects 

Fish 


Pond  Numbers — Ecological  Age-Series 


20 

32 
80 
o 
20 
10 

50 

10 

40 

100 


60 

35 
80 

50 
50 
50 
90 
SO 
90 

87 


146 


100 
100 
100 
100 
100 
100 
100 
100 
100 
87 


The  Entomostraca  are  rated  on  the  basis  of  actual  count  of  six  col- 
lections.    The  other  figures  are  estimates  (6). 

Here  we  note  that  the  number  of  Entomostraca  was  greater  in  the 
older  ponds  though  some  irregularities  occur,  dependent  upon  the 
amount  of  rainfall.  In  rainy  seasons  the  increase  with  age  appears 
almost  throughout. 

As  we  pass  from  younger  to  older  ponds  we  note  an  increase  in  the 
number  of  animals,  excepting  fish.    These  appear  to  decrease,  probably 


70 


AQUATIC  CONDITIONS 


because  of  the  increasing  unsuitability  of  the  ponds  as  fish  breeding- 
places.  The  oxygen  content  decreases,  particularly  on  the  bottom. 
The  distribution  of  the  fish  present  in  these  ponds,  and  whose  breeding 
habits  were  known,  was  found  to  be  correlated  with  the  distribution 
of  the  bottom  upon  which  they  breed.  This  becomes  less  and  less  in 
amount  as  the  ponds  grow  older. 

3.      EQUILIBRIUM 

Each  animal  prefers  certain  food.  The  food  relations  of  pond 
animals  are  shown  in  Diagram  3,  below.  For  purposes  of  illustration 
let  us  suppose  the  existence  of  a  community  composed  of  the  species 
named  only. 


Pickerel^ 


Diagram  3. — Showing  food  relatfons  of  aquatic  animals.  Arrows  point  from  the 
organisms  eaten  to  those  doing  the  eating.     For  explanation  see  text. 

Any  marked  fluctuation  of  conditions  is  sufificient  to  disturb  the 
balance  of  an  animal  community  (see  chap,  i,  p.  18).  Let  us  assume 
that  because  of  some  unfavorable  conditions  in  a  pond  during  their 
breeding  period  the  black  bass  (79)  decreased  markedly.  The  pickerel, 
which  devours  young  bass,  must  feed  more  exclusively  upon  insects. 
The  decreased  number  of  black  bass  would  relieve  the  drain  upon  the 
crayfishes,  which  are  eaten  by  bass,  crayfishes  would  accordingly  increase 
and  prey  more  heavily  upon  the  aquatic  insects.  This  combined  attack 
of  pickerel  and  crayfishes  would  cause  insects  to  decrease  and  the  number 
of  pickerel  would  fall  away  because  of  the  decreased  food  supply.  Mean- 
while the  bullheads,  which  are  general  feeders  and  which  devour  aquatic 
insects,  might  feed  more  extensively  upon  mollusks  because  of  the 


EQUILIBRIUM 


71 


decrease  of  the  former  (see  chap,  i,  p.  15),  but  would  probably  decrease 
also  because  of  the  falling-off  of  their  main  article  of  diet.  We  may 
thus  reasonably  assume  that  the  black  bass  would  recover  its  numbers 
because  of  the  decrease  of  pickerel  and  bullheads,  the  enemies  of  its 
young.  A  further  study  of  the  diagrams  shows  that  a  balance  between 
the  numbers  of  the  various  groups  of  the  community  would  soon  result. 


Diagram  s 


Diagram  4. — Showing  the  life  histories  of  the  animals  of  the  pond  community 
in  the  form  of  circles.  The  heavy,  vertical,  black  lines  represent  the  animals  which  are 
dependent  upon  the  most  elementary  food  substances.  A  represents  dead  animal 
matter;  B,  the  protozoa,  rotifers,  and  Entomostraca,  the  smallest  animal  food.  The 
black  lines  come  into  contact  with  different  numbers  of  life  cycles,  but  are  indirectly 
connected  with  all  so  that  any  change  in  the  position  or  rate  of  movement  (meaning 
number  or  rate  of  reproduction  and  growth)  of  the  rod  must  effect  the  entire  com- 
munity; compare  with  Diagram  3. 

Diagram  5. — Showing  the  food  relations  in  the  brook  communit3^  A  repre- 
sents algae  which  grow  upon  the  stones.  B  represents  the  floating  animal  bodies  and 
other  organic  matter.  The  latter  are  of  small  importance  because  of  their  small 
number  and  the  swift  current. 


Under  other  circumstances,  such  as  the  extinction  of  the  black  bass,  the 
resulting  condition  would  be  entirely  different  from  the  original  one, 
but  a  balance  between  supply  and  demand  would  nevertheless  finally 
be  established.  The  community  is  said  to  have  equilibrated  when  such  a 
condition  is  reached;  that  is,  a  new  equilibrium  is  established  which 
may  or  may  not  be  like  the  old. 


72  AQUATIC  CONDITIONS 

The  causes  of  fluctuations  of  numbers  of  organisms  are  numerous. 
Cold  winters  often  destroy  aquatic  vertebrates.  Large  rainfall  dilutes 
the  plankton  in  streams  and  carries  it  away.  Too  little  sunshine  causes 
a  poor  production  of  the  chlorophyll-bearing  organisms  which  are  the 
food  basis  of  all  the  others.  High  temperature  favors  denitrification. 
From  Diagram  3  and  brief  discussion  above  it  will  be  seen  that  there 
are  in  a  pond  community,  close  interrelations  traceable  to  certain  groups 
which  are  closely  dependent  upon  the  more  elementary  food  substances. 
A  representation  of  these  relations  is  given  in  Diagrams  4  and  5. 


CHAPTER  V 
ANIMAL  COMMUNITIES  OF  LARGE  LAKES  (LAKE  MICHIGAN) 

1.  Conditions 

I.      GENERAL    (75) 

Lake  Michigan  lies  between  4i°-4o'  and  46°-5'  N.  latitude.  Its  total 
length  is  about  350  miles  and  its  greatest  width  is  approximately  85  miles. 
Its  area  is  about  25,000  sq.  miles.  Its  greatest  depth  is  nearly  275  meters 
(900  ft.)  and  its  average  depth  is  approximately  122  meters  (400  ft.). 

Within  the  area  covered  by  our  map  (frontispiece)  there  are  about 
3,200  sq.  miles.  The  maximum  depth  is  about  152  meters  (500  ft.). 
It  has  been  estimated  that  the  lake  contains  262,500,000,000,000  cubic 
feet  of  water.  It  becomes  obvious  at  once  that  the  lake  constitutes  one 
of  the  most  uniform  and  extensive  environments  with  which  we  have  to 
deal. 

2.  CIRCULATION 

The  level  of  the  lake  fluctuates  from  season  to  season  with  the 
amount  of  rainfall,  but  we  have  been  unable  to  find  a  statement  as  to  the 
amount  of  such  fluctuation.  Changes  in  atmospheric  pressure  over  part 
of  the  lake  cause  various  fluctuations  in  level,  called  seiches.  In  Lake 
Michigan  there  is  a  definite  circulation  of  the  surface  waters.  Here  the 
current  moves  southward  alon^  the  west  shore  (57),  around  the  head  of 
the  lake,  and  northward  along  the  east  shore.  The  rate  of  flow  is  4  to  90 
miles  per  day. 

II.    Communities  of  the  Lake*  (80,  81,  82,  83,  84) 

One  of  the  recognizable  animal  communities  of  Lake  Michigan  is 
made  up  of  the  animals  which  live  freely  in  the  water,  either  swimming 
or  floating.  This  community  is  called  the  Pelagic  or  Limnetic  com- 
munity.    Other  communities  are  governed  directly  or  indirectly  by  depth 

'  The  only  published  account  of  the  invertebrate  fauna  of  the  Great  Lakes  is 
that  of  Lake  Superior.  From  this  account  and  from  incidental  scattered  notes  found 
in  various  publications  cited  we  have  been  able  to  bring  together  enough  data  to  give 
an  idea  of  the  conditions  and  life  which  we  may  expect  future  investigations  to  show. 
The  attempts  to  study  Lake  Michigan  have  been  ill-fated.  In  187 1,  the  Chicago 
Academy  of  Sciences  and  the  United  States  Fish  Commission  co-operated  in  an 
attempt  to  study  the  fauna  of  the  lake.     The  work  on  the  vertebrates  was  published 

73 


74 


COMMUNITIES  OF  LARGE  LAKES 


and  bottom.     Accordingly  the  conditions  on  the  bottom  at  various 
depths  are  roughly  shown  in  Table  IX. 


TABLE  IX 


Depth 

Vegetation 

Meters 

Feet 

Limit  of  sand-moving  waves 

Limit  of  daily  temperature  fluctua- 
tions;  limit  of  wave  action;    be- 
ginning of  light  decrease;  pressure 
about  2\  atmospheres 

8 

25 
39 

54 
70 

"5 

153 
274 

26 

82 
128 

177 
230 

377 
500 
900 

Lowest  record  of  Chara 

Pressure  4  atmospheres;    light  re- 
duced to  5 

and  (75)  Cladophora 
Scanty  filamentous  algae 

Seasonal   temperature   fluctuations 
less  than  1°;   light  reduced  to  |; 
pressure  5*  atmospheres 

Light  5 ;  pressure  7  atmospheres .  . . 

No  light;  pressure  ii|  atmospheres; 
no  change  in  temperature;  uni- 
form conditions      

(75) 

Nosloc  and  diatoms  (75) 
No  bottom  plants  recorded 

No  plants  recorded 

Greatest   depth   in    the   area   con- 
sidered; pressure  15  atmospheres 

Greatest  depth  in  lake;  pressure  27I 
atmospheres 

No  plants  recorded 
No  plants  recorded 

I.      THE   LIMNETIC   COMMUNITY 

(Station  1 ;  List  I) 
Chicago  is  famous  for  its  good  water  supply.  However,  if  one  fastens 
a  small  sack  of  miller's  bolting-cloth  under  an  open  water  tap  for  an 
hour  in  summer  and  examines  the  contents  of  the  sack  with  the  naked 
eye  and  then  with  the  microscope,  he  will  be  of  the  opinion  that  he  has 
not  been  straining  drinking  water  but  stagnant  ditch  water.  He  finds 
small  microscopic  plants  in  great  numbers  (75),  as  well  as  large  numbers 
of  small  animals,  most  of  the  larger  ones  dead.  Every  person  drinking 
water  from  a  lake  or  river  drinks  the  small  plants  and  animals.  If 
every  one  of  the  2,000,000  persons  in  Chicago  drank  a  quart  of  unfiltered 

by  the  United  States  Fish  Commission,  and  Doctor  Stimpson  of  the  Academy  pub- 
lished a  brief  note  on  the  invertebrate  forms  found  in  the  lake,  but  never  gave  more 
than  a  hint  of  the  work,  as  the  collections  were  aU  burned  with  the  Academy's  build- 
ing. Subsequently,  collections  were  made  by  the  State  Laboratory  of  Natural  His- 
tory, and  later  by  the  Fish  Commissioners  of  Michigan.  In  the  siunmer  of  1902,  the 
University  of  Chicago  and  the  Academy  of  Sciences  made  a  single-day  excursion, 
but  no  report  was  ever  published. 


LIMNETIC  COMMUNITY 


75 


city  water  in  a  day  in  August,  all  together  they  would  be  consuming 
about  lo  quarts  of  solid  plant  and  animal  substance — enough  to  make 
a  meal  for  about  forty  people. 

One  does  not  think  of  the  lake  as  an  area  of  luxuriant  vegetation, 
teeming  with  animal  life,  but  rather  as  a  barren  waste  of  water.  How- 
ever, if  one's  vision  for  small  objects  were  only  better,  he  would  see  as 
he  passes  over  the  water  in  a  boat,  thousands  of  small  animals  and  plants 
such  as  are  shown  in  Figs.  12-18  together  with  about  fifty  other  forms  of 
protozoa,    wheel    animal-  , 

// 

iJ/ 


-^•^  .y-  ■■% 


'"^■m^ 


12 


cules,  crustaceans,  insects, 
and  small  fish.  Most  of 
these  spend  their  entire 
existence  freely  floating  or 
freely  swimming.  With 
the  exception  of  the  fish 
and  insects  they  consti- 
tute the  plankton  which  is 
the  basis  of  the  food  of  the 
millions  of  pounds  of  fish 
taken  from  Lake  Michigan 
every  year. 

From  the  standpoint 
of  our  economic  interests, 
the  limnetic  formation 
is  of  great  importance. 
It  deserves  comment  also 
because  of  its  scientific 
interest,  and  the  aes- 
thetic value  of  the  vari- 
ous forms  of  which  it  is 
composed. 

a)  Its  composition  (85,  86,  87,  88,  89). — The  minutest  animals  of 
this  formation  are  the  protozoa.  About  thirteen  species  have  been  found 
to  inhabit  the  open  waters  of  the  lake.  Of  these  the  sun  animalcule 
(Actinophrys  sol)  (Fig.  12)  and  the  shelled  protozoan  {Difflugia  globu- 
losa)  (Fig.  14)  are  easiest  to  recognize.  Nine  of  the  thirteen  common 
species  are  mixotrophic  in  their  nutrition  (i.e.,  contain  chlorophyll  and 
manufacture  their  own  food)  (Fig.  13)  and  share  with  the  algae  and 
diatoms  the  important  function  of  furnishing  food  for  the  rotifers  (wheel 
animalcules)  and  the  crustaceans. 


Fig.  12. — A  sun  animalcule  {Actinophrys  sol 
Ehrbg.);  330  times  natural  size  (after  Leidy). 

Fig.  13. — Protozoan  {Peridinium  tabulatum 
Ehrbg.);  400  times  natural  size  (after  Kent). 

Fig.  14. — A  shelled  protozoan  {Difflugia  globu- 
losa  Duj.);  130  times  natural  size  (after  Leidy). 


76 


COMMUNITIES  OF  LARGE  LAKES 


About  a  dozen  species  of  crustaceans  are  common  in  the  lake.  They 
feed  chiefly  on  the  protozoa,  diatoms,  desmids,  and  possibly  the  rotifers 
(85).  Such  crustaceans  constitute  almost  the  sole  food  of  young  fishes  and 
are  the  first  food  of  the  young  whitefishes  (79).  They  are  divided  into 
copepods  and  Cladocera  (and  ostracods,  rare).  This  division  of  the 
crustaceans  is  known  as   the  Entomostraca.     The  smallest  and  most 


Representative  Crustaceans  and  Rotifers  of  the  Limnetic  Community  of 

Lake  Michigan 

Fig.  15. — A  common   copepod   {Cyclops  bicuspidatus);    25   times  natural  size 
(after  Forbes). 

Fig.  16. — A  cladoceran  {Bosmina);  enlarged  (from  Forbes  after  Gerstaecker) . 
Fig.  17. — A  cladoceran  {Daphne  hyalina  galeata);  enlarged  as  indicated  (after 
Smith) . 

Fig.  18. — A  pelagic  rotifer  {Notops  pelagicus  Jen.);  180  times  natural  size  (after 
Jennings) . 

Fig.  19. — The  same,  side  view. 


abundant  of  the  Entomostraca  of  the  lake  is  only  i .  i  mm.  in  length  and 
is  slender  and  colorless.  It  is  the  slender  Cyclops  bicuspidatus,  shown 
in  Fig.  15. 

The  commonest  C/a(/ocem  of  the  lake  are  Bosmina  (Fig.  16),  Daphne 
retrocurva,  and  Daphne  hyalina  (Fig.  17).  One  other  small  species 
{Leptodora  hyalina)  belonging  to  this  group  is  a  very  interesting  creature. 


SHALLOW  WATER  COMMUNITIES  77 

"When  in  its  native  element  it  is  almost  perfectly  transparent  and 
consequently  invisible — a  true  microscopic  ghost"   (Forbes,  89). 

The  wheel  animalcules  are  as  a  rule  larger  than  the  protozoa  and  are 
of  a  much  higher  structural  organization,  capable  of  making  more 
complex  movements.  About  thirteen  species  of  these  may  be  found  in 
the  waters  of  the  lake  in  midsummer.  Notops  p'ygmaeus  Calm,  (see 
Figs.  18-19)  is  a  characteristic  member  of  the  group. 

In  addition  to  these  forms  there  are  also  worms,  such  as  round  worms, 
planarians,  leeches,  etc.,  found  in  the  limnetic  formation  either  inciden- 
tally or  habitually. 

None  of  the  adult  fishes  of  the  lake  belong  strictly  to  the  limnetic 
formation.  Fishes  such  as  the  whitefish,  lake  herring,  and  lake  trout 
are  sometimes  found  in  the  open  water,  and  the  young  of  some  lake 
fishes  may  belong  there  strictly  (90). 

b)  Characters. — Specialists  in  the  various  groups  of  animals  might  be 
able  to  pick  out  some  structural  characters  which  would  distinguish 
the  forms  of  such  open-water  situations  from  the  forms  living  in  among 
the  vegetation  or  on  the  bottoms  of  this  or  smaller  lakes.  The  only 
striking  structural  character  is  the  transparent  or  translucent  color  of 
most  of  the  forms. 

A  large  number,  if  not  all,  of  the  limnetic  crustaceans  are  in  deep 
water  during  the  day  and  come  to  the  surface  at  night.  The  behavior 
of  the  rotifers  is  somewhat  different.  Jennings  (87)  says:  "During 
the  day  the  limnetic  rotifers  are  found  in  much  greater  numbers  near 
the  surface  than  near  the  bottom,  reversing  the  condition  commonly 
observed  for  the  crustaceans.  At  night  the  distribution  seems  not  to  be 
materially  changed.  The  immense  numbers  of  crustaceans  obscure  the 
rotifers;  but  there  was  no  greater  number  of  rotifers  near  the  bottom 
in  the  few  to  wings  made  at  night  than  in  the  day  time." 

The  most  striking  characteristic  of  the  limnetic  formation  is  that  it  is 
independent  of  bottom  and  in  its  reactions  is  indifferent  to  the  bottom. 
Jennings  (44)  states  that  pelagic  forms  have  a  more  simple  type  of 
behavior  than  the  attached  and  bottom  forms. 

2.      BOTTOM   COMMUNITIES 

Forms  inhabiting  the  bottom  of  lakes  and  also  of  the  sea  in  a  general 
way  bear  the  same  relation  to  the  water  that  the  terrestrial  animals  do 
to  the  surface  of  the  land.  Usually  they  do  not  leave  it  to  rise  to  any 
considerable  height  above  the  bottom.  The  fishes  of  lakes  correspond 
to  the  birds  of  the  land. 


78  COMMUNITIES  OF  LARGE  LAKES 

Other  relations  are,  however,  different.  As  has  been  stated,  there 
are  no  truly  rooted  plants  in  the  bottom  of  Lake  Michigan.  Those 
attached  to  the  bottom  are  not  rooted  in  the  way  that  land  plants  are. 
The  things  which  land  plants  get  from  the  soil  are  supplied  to  the  aquatic 
plants  by  the  water  itself.  The  same  is  true  of  the  bottom  animals; 
food  is  floating  in  the  water  in  quantities  and  can  accordingly  be  secured 
without  effort,  and  some  animals  have  the  form  of  plants  and  simply 
depend  upon  the  food  which  may  be  brought  within  reach  by  accident. 

Classification  of  bottom  formations:  Bottom  formations  are  de- 
termined by  depth  (and  associated  phenomena)  and  bottom.  Bottom 
is  of  greatest  importance  in  shallow  water  (less  than  8  meters).  Its 
importance  is  inversely  proportional  to  depth. 

Within  the  zone  of  wave-action  conditions  are  somewhat  different 
than  below  it.  Here  the  kind  of  animals  is  determined  by  (i)  strength 
of  wave-action,  (2)  erosion  and  kind  of  material  eroded,  and  (3)  deposi- 
tion, and  animal  communities  may  be  classified  as  those  of  (i)  eroding 
— rocky  or  stony — shores,  (2)  depositing  or  sandy  shores,  and  (3)  pro- 
tected situations. 

a)  Eroding  rocky  shore  sub-formation  (80,  81,  82,  83,  84)  (Stations 
la,  2 ;  Table  XV). — There  are  a  considerable  number  of  rock  outcrops  in 
the  bottom  inside  the  8-meter  (26  ft.)  line,  between  Gross  Point  and  the 
mouth  of  the  Calumet  River  at  South  Chicago  (61).  As  we  shall  see 
later,  these  are  of  great  importance  to  the  animals  of  the  lake.  However, 
the  communities  of  such  situations  are  known  to  us  only  through  the 
study  of  the  very  shallow  water  in  the  vicinity  of  Glencoe.  Here,  attached 
to  the  rocks  by  their  silk,  are  caddis- worms  (Hydropsyche).  (Mr.  W.  J. 
Saunders  has  given  me  specimens  of  Parnidae  (Psephenus)  and  stone-fly 
nymphs  (Perla)  taken  from  Lake  Ontario  at  Kingston,  Ontario.)  All 
these  ordinarily  live  in  swift  streams.  Under  the  stones  and  among 
the  algae  attached  to  them  are  amphipods  {Hyalella  knickerh-ockeri) 
and  May-fly  nymphs  (Ephemeridae) ,  but  so  far  as  we  have  been  able  to 
record  these  are  the  only  forms  common  here.  The  animals  avoid  the 
waves  by  creeping  under  stones  or  are  attached  to  withstand  wave- 
action.  The  lake  trout  (Fig.  20)  is  known  to  breed  on  the  rocks  off 
Lincoln  Park.  These  rocks  are  then  of  considerable  importance  to  the 
fish.  Some  species  of  small  fish  may  be  common  here,  but  they  have 
not  been  studied. 

b)  Sandy  depositing  shore  sub-formation,  0-8  meters  (26  ft.),  shifting 
sand  bottom  (Station  3;  Table  XII). — On  the  open  shore  inside  of  1.5 
meters  (5  ft.)  of  water  we  have  found  nothing  on  the  bottom.     From  this 


SHALLOW  WATER  COMMUNITIES 


79 


depth  to  4  meters  (13  ft.)  Sphaerium  vermontanum,  which  occurs  rarely 
in  Hickory  Creek  also,  and  midge  larvae  (a  red  and  a  white  species) 
appear  characteristic.  A  number  of  species  of  small  fish  such  as  the 
blunt-nosed*  minnow,  the  straw-colored  minnow,  and  shiners  are  likely 
to  be  found  in  from  4-8  meters  (13-26  ft.)  of  water.  An  occasional 
Lymnaea  woodruffi,  is  found  at  this  depth. 


Representative  Fishes  Belonging  Mainly  to  the  Tr.\nsition  Belt  of 
Lake  Michigan  (25-54  m.) 

Fig.  20.— Great  Lakes  trout  {Cristivomer  namayctish);  length  3  feet  (after  Jordan 
and  Evermann). 

Fig.  21.— The  long-jaw  vvhitefish  {Argyrosomus  prognathus);  length  15  inches; 
from  the  depth  of  74  meters  (after  Smith). 

c)  Communities  of  protected  situations  (Table  X).— Near  Chicago, 
bays  and  inlets  are  rare.  Doubtless  the  mouths  of  some  of  the  larger 
rivers  before,  they  were  modified  for  navigation,  were  of  this  character. 
Such  places  have  been  studied  in  Lake  Superior  (80,  ^t,)  and  the  Grand 
Traverse  Bay  region.     Out  of  21  species  recorded  here,  16  are  definitely 


8o  COMMUNITIES  OF  LARGE  LAKES 

recorded  below  9  meters  and  not  on  the  open  shores.     All  are  found  in 
small  lakes  and  sluggish  streams. 

d)  Lower  shore  formation  (8-25  meters)  (Station  3;  Tables  XI,  XIII, 
XV).— The  belt  immediately  below  the  shore  belt  is  characterized  by 
wave-action  sufficient  to  move  only  the  finest  material.  Its  lower  limit 
is  the  limit  of  wave-action;  the  beginning  of  light  diminution;  the  lower 
limit  of  daily  fluctuation  in  temperature;  and  the  lower  limit  for  most 
of  the  species  of  Mollusca  (75,  appendix).  Practically  all  the  forms  that 
have  been  recorded  here  are  inhabitants  of  still,  shallow  water  also. 
Notable  among  these  are  the  common  still-water  amphipod  Eucrangonyx 
gracilis,  the  little  bivalve  Sphaerium  striatinum,  and  several  species  of 
Amnicola  and  Valvata  which,  together  with  Lymnaea  woodruffi,  are  more 
characteristic  of  Lake  Michigan  than  of  shallow  waters.  While  a  large 
number  of  Mollusca  are  recorded  from  the  lake  above  25  meters  only  the 
Sphaeridae  are  found  below  this  limit.  Small  annelids,  midge  larvae, 
and  leeches  are  very  abundant  north  of  Gary,  Ind.,  in  1 1  meters  of  water. 

This  belt  is  the  principal  breeding-ground  of  the  whitefish.  The 
eggs  are  deposited  on  the  bottom  and  left  unguarded.  It  appears  that 
the  young  fish  stay  in  the  shallow  waters  for  a  considerable  time.  Wher- 
ever the  bottom  is  firm  the  lake  trout  breeds  also.  Nearly  all  the  fish 
traps  are  set  in  the  upper  edge  of  this  belt  and  in  the  lower  boundary  of 
the  one  above. 

e)  Belt  of  overlapping:  upper  deep-water  belt  (25-54  meters)  (Tables 
XIV,  XV). — This  belt  is  characterized  as  below  wave-action,  below 
daily  fluctuations  of  temperature,  with  seasonal  fluctuations  not  exceed- 
ing f  C.  It  is  intermediate  between  the  belt  above  and  the  deep  belt, 
and  is  the  characteristic  feeding-ground  of  the  whitefish  and  the  regular 
home  of  the  long-jaw  (Argyrosomus  prognathus,  Fig.  21).  On  the  other 
hand,  it  is  the  upper  limit  for  some  of  the  deeper-water  forms,  such  as  the 
well-known  Mysis  relicta  and  Pontoporeia  hoyi  (Figs.  22,  23),  the  deep- 
water  crustaceans  which  are  the  chief  food  of  the  whitefish. 

f)  Deep-water  formation  (54  meters  to  bottom)  (Table  XV). — This 
belt  is  characterized  by  weak  or  no  light  and  by  seasonal  changes  in 
temperature  less  than  i  degree.  Below  115  meters  there  are  no  light 
and  no  seasonal  changes,  and  the  temperature  is  4°  C.  throughout  the 
year.  Off  Racine  in  82  metefs  (265  ft.)  the  bottom  is  of  reddish-brown 
sandy  mud  (82);  in  95-125  meters  (311-410  ft.)  dark-colored  impalpable 
mud,  depressions  with  decaying  leaves  (82a).  In  the  Grand  Traverse 
Bay  region,  Milner  found  decaying  sawdust  in  183  meters  (600  ft.)  (81). 
Except  for  unimportant  variation  in  bottom,  conditions  are  practically 
uniform   throughout.     Milner   (81)   states   that  the  invertebrates  are 


SUMMARY  81 

abundant  and  evenly  distributed  throughout  the  deep-water  belt.  The 
principal  invertebrates  are  Pontoporeia  hoyi,  Mysis  relicta,  water-mites, 
midge  larvae,  and  a  species  of  Pisidium. 

The  fish,  however,  show  some  noteworthy  peculiarities  of  distribution. 
The  lake  trout  rarely  leaves  this  belt,  except  during  the  breeding  season. 
The  blackfin  {Argyrosomus  nigripinnis)  is  below  70  meters,  except  in 
December,  when  it  has  been  recorded  in  60  meters.     Hoy's  whitefish 


Representative  Crustaceans  of  the  Deep-Water  Community  of 
Lake  Michigan 

Fig.  22. — A  schizopod  {Mysis  relicta);  enlarged  as  indicated  (after  Smith). 
Fig.  23. — An  amphipod  {Pontoporeia  hoyi)  (after  Smith). 

{Argyrosomus  hoyi)  is  rare,  and  Triglopsis  thompsoni  has  not  been 
recorded  above  115  meters;  all  accordingly  live  under  uniform  condi- 
tions— no  day,  no  night,  no  seasons. 

III.     Summary 

The  available  data  on  the  conditions  and  life  in  the  lake  are  of  such 
a  nature  as  to  justify  few  conclusions  of  weight.  We  find  only  hints 
here  and  there  which  may  be  useful  to  those  who  shall  investigate  the 
lake  in  the  future. 

I.  Bottom  forms  are  the  most  abundant  on  the  open  shores  which 
are  rocky,  and  which  form  good  substrata  for  the  attachment  of  algae 
and  the  holdfast  organs  of  animals. 


82  COMMUNITIES  OF  LARGE  LAKES 

2.  The  sand-depositing  shores  are  without  animals,  at  least  to  a  depth 
of  1 . 5  meter,  and  life  is  scanty  to  8  meters,  on  account  of  the  shifting 
character  of  the  bottom. 

3.  Animals  are  abundant  in  protected  bays;  the  species  inhabiting 
these  situations  are  commonly  found  in  sluggish  streams  and  small 
lakes,  and  a  few  of  them  have  been  recorded  below  8  meters  also,  which 
is  relatively  quiet  water. 

4.  The  animals  of  the  upper  shore  belt,  0-8  meters,  are  found  also 
in  swift  streams. 

5.  The  animals  of  the  lower  shore  and  upper  deep-water  zone  are 
below  effective  wave-action  and  are  those  found  in  still  waters. 

6.  The  animals  of  the  deep-water  zone  are  not  found  outside  of  deep 
lakes,  and  cannot  be  compared  with  any  others  of  our  Chicago  area. 

7.  We  have,  then:  swift- water  animals  in  the  upper  belt,  still- water 
animals  in  the  middle  belt,  and  deep-water  animals  in  the  lowest. 

8.  The  fish  are  migratory  and  deserve  special  comment. 

DISTRIBUTION   OF   WHITEFISH  AND   DEEP-WATER   FISH  IN   LAKE   MICHIGAN    (75) 

Argyrosomus  artedi,  the  lake  herring,  is  near  the  surface. 

Coregonus  clupeijormis,  the  whitefish,  lives  most  commonly  between  21  and 

36  meters;  it  spawns  in  water  between  3  and  28  meters,  most  commonly 

between  15  and  19  meters.    It  makes  migrations  into  the  9-meter  belt 

in  summer,  supposedly  on  account  of  bad  aeration;  has  disappeared 

where  breeding-grounds  have  been  destroyed. 
Argyrosomus  prognathus,  the  long-jaw,  is  found  mainly  in  from  36-66  meters. 
Argyrosomus  nigripinnis,  the  blackfin,  is  found  in  from  70-80  meters,  coming 

up  to  60  in  December. 
Argyrosomus  hoyi,  Hoy's  whitefish,  is  usually  recorded  below  115  meters. 
Triglopsis  thompsoni  is  confined  below  115  meters. 
Cristivomer  namaycush,  the  lake  trout,  is  confined  below  25  meters,  except 

during  the  breeding  season.     It  breeds  between  2  and  25  meters  on  rock 

or  other  hard  bottom. 
Loia  maculosa,  the  lawyer,  appears  to  be  distributed  throughout,  but  no 

account  is  to  be  found  regarding  its  movements  or  their  causes. 

An  interesting  truth  is  illustrated  by  the  species  of  whitefishes 
{Argyrosomus  and  Coregonus).  If  a  group  is  to  be  successful  and  become 
extensive  in  its  distribution,  it  must  so  differentiate  in  habits  as  to  bring 
the  different  races  out  of  competition  with  each  other.  We  usually 
find  that  different  species  which  are  closely  related  have  different  habitats. 
Here  we  have  these  species  of  fish  arranged  one  above  the  other.  The 
separation  in  such  cases  is  usually  horizontal. 


ANIMALS  OF  LARGE  LAKES 


83 


Animals  Recorded  from  Lake  Michigan' 
LIST  I 

Common  Entomoslraca 
Copepods:   Cyclops  leuckarti  Claus,  C.  biciispidatus  Claus,  C.  prasinus  Fischer, 
Epischiira  lacustris  Forbes,  Diaptomus  ashlandi  Marsh,  D.  oregonensis  Lil.;   Clado- 
cerans:   Daphne  hyalina  Ley.,  and  D.  retrocurva  Forbes. 


TABLE  X 

Animals  occurring  in  protected  situations  (bays,  harbors,  etc.)  in  Lake  Superior 
in  from  0-2  meters  of  water,  and  known  also  to  occur  in  Lake  Michigan  where  habitats 
are  not  recorded: 


Common  Name 

Scientific  Name 

Literature 

Mussel 

Auodonla  grandis  Say 

(75,  83,  91) 
(75,83,91) 
(75,  83,  91) 
(75,83,91) 

Mussel 

Auodoiild  maTginata  Say 

Snail 

Amnicola  lustrica  Pils 

Snail 

Valvata  Iricarinata  Say 

TABLE  XI 

Animals  of  the  lower  shore  belt.  Those  definitely  recorded  from  8-15  meters  of 
water  are  marked  *  and  **,  the  latter  indicating  that  the  records  are  original  from 
II  meters  of  water  north  of  Gary,  Ind.  (Station  3);  f  indicates  that  the  animals 
are  recorded  from  protected  bays  in  0-2  meters  of  water  (Lake  Superior),  and  H 
that  they  occur  in  inland  waters,  especially  ponds: 


Common  Name 


Scientific  Name 


tH    SnaU 

tH    Snail 

tH    Snail 

t1f**Snail 

t1I**Snail 

t1I**Snail 

n**Snail 

**Snail 

tH     Snail 

t    **Bivalve 

t1[**Bivalve 

t1f**Bivalve 

n*  Bivalve 

tH*  Bivalve 

n*  Bivalve 

t1[**Bivalve 

t1f**Bivalve 

li*  Midge  larva. 

V  Leech 

1[**Worm 


Lymnaea  stagnalis  Linn 

Planorbis  bicar hiatus  Say 

Planorbis  exacutus  Say 

Amnicola  Umosa  Say 

Amnicola  Umosa  porata  Say 

Amnicola  emarginata  Kiister 

A  mnicola  lustrica  Pils 

Valvata  bicarinala  perdepressa  Walk. 

Valvata  sincera  Say 

Pisidium  idahoense  Roper 

Pisidium  scutellatum  Sterki 

Pisidium  compressum  Prime 

Pisidium  variabile  Prime 

Pisidium  ventricosum  Prime 

Pisidium  punctatum  Sterki 

Sphaerium  striatinum  Lamarck 

Calyculina  transversa  Say 

Metriocnemis  sp 

Glossiphonia  stagnalis  Linn , 

Limnodrilus  claparedianus  Ratzel..  .  . 


Literature 


(75,  83,  91) 

(75,  83,  91) 

(75,83,91) 

(91) 

(91) 

(91) 

(91) 

(91) 

(75,  83) 
(83.  91) 
(91) 
(75,  83,  91) 

(75,  ^i,  91) 

(75,  91) 
(80) 

(91) 

X 
(91a) 


X  See  citation  q8. 

'The  numbers  in  parentheses  in  the  column  headed  "Literature"  refer  to  refer- 
ences in  the  Bibliography  at  the  end  of  the  bock. 


84 


COMMUNITIES  OF  LARGE  LAKES 


TABLE  XII 

Animals  on  depositing  shores  in  from  0-8   meters   of  water,   *  indicating  that 
records  are  original. 


Common  Name 


Scientific  Name 


Literature 


*Blood\vorm 

*Bivalve 

*Midge  larvae 

*Snail 

Long-nosed  sucker.  .  . 

Common  sucker 

Hog  sucker 

Red-horse 

*Trout  perch 

Minnow 

Straw-colored  minnow 

*Shiner 

*Blunt-nosed  minnow. 

Top  minnow 

Johnny  darter 

Least  darter 

Lake  herring 

Pumpkinseed 

Bluegill 

Mud  minnow 

Eel • 


Chironomid  larvae 

Sphaerium  vermontanum  Prime  (characteris 

tic) 

Metriocnemns  sp 

Lymnaea  woodruffi  Baker  (rarely) 

Catostomus  caiostomiis  Fors 

Calostomus  commersonii  Lac 

Catostomus  nigricans  LeS 

Moxostoma  aureolum  LeS 

Percopsis  guliatus  Ag 

Notropis  hudsoniiis  DeW.  Clin 

Notropis  blennius  Gir 

Notropis  atherinoides  Raf 

Pimephales  notatus  Raf 

Fundulus  diaphanus  menonaj.  and  C.  .  .  . 

Boleosoma  nigrum  Raf 

Microperca  punctulata  Put 

Argyrosomus  anedi  LeS 

Eupomotis  gibhosus  Linn 

Lepomis  pallidus  Mitch 

Umbra  limi  Kirt 

AnguiUa  rostrata  LeS 


(81,  84) 

(81,  84) 

(81.  84) 

(81,  84) 

(81) 

(84) 

(84) 

(84) 

(84) 

(84) 

(84) 

(84) 

(75-  84) 

(81) 

(81) 

(81) 

(81,  84) 


TABLE  XIII 
Animals  occurring  in  from  15-25  meters  of  water: 


Common  Name 


Scientific  Name 


Literature 


Snail.  .  .  . 
Polyzoan 
Snail.  .  .  . 
Snail.  .  .  . 
Leech.  .  . 
Larvae.  . 
Rotifer.  . 
Rotifer.  . 


Amnicola  walker i  Pils.  .  .  . 

Plumatella  sp 

Pleuroceridae 

Lymnaea  sp 

Clepsine  sp 

Neuropteroid  insects.  .  .  . 
Rotifer  elongatus  Weber  .  . 
Dinocharis  tetractis  Ehrbg 


(75,  83) 
(81,  82) 
(81,  82) 
(81,  82) 
(81,  82) 
(81,  82) 
(75) 
(75) 


TABLE  XIV 
Animals  occurring  in  from  25-54  meters  of  water: 


Common  Name 

Scientific  Name 

Literature 

Bivalve 

(82) 

Polyzoan 

Paludicella  ehrenbergii  van  Ben 

(75) 

Polvzoan 

Fredericella  sultana  Blum 

(75) 

ANIMALS  OF  LARGE  LAKES 


85 


TABLE  XV 

Showing  the  recorded  distribution  of  animals  occurring  in  several  of  the  vertical 
belts  of  Lake  Michigan.  The  star  indicates  that  the  animal  is  present  at  the 
depth  indicated  at  the  head  of  the  column  in  which  the  star  occurs.  B  indicates 
that  it  breeds,  and  F  that  it  feeds,  at  the  indicated  levels.  The  numbers  in  the 
column  headed  "Literature"  refer  to  the  Bibliography  at  the  end  of  the  book. 
The  lower  depth  limit  of  many  of  the  fishes  listed  is  somewhat  uncertain,  as 
Milner  does  not  indicate  their  exact  distribution  inside  of  35  meters,  but  implies 
that  thej^  may  occur  at  the  depths  indicated  in  the  table.  Other  records  bear 
out  Milner's  implications. 


Common  Name 


Sturgeon 

Crayfish 

Crayfish 

Long-nosed  gar 

Lake  catfish 

Croaker 

Perch 

Wall-eyed  pike 

Large-mouthed  black 

bass 

Small-mouthed  black 

bass 

Northern  moon-eye .  . 

Toothed  herring 

Tadpole  cat 

Carp 

Pike 

Brook  silverside 

Stickleback 

Whitefish 

Rock  bass 

Amphipod 

Snail 

Long-jaw 

Lawyer 

Lake  trout 

Hoy's  whitefish 

Amphipod 

Schizopod 

Blackfin 

Small  cottoid 


Scientific  Name 


Acipenser  rubicimdiis  LeS. 
Cambarus  propinquus  Gir. 

Cambarits  virilis  Hag 

Lepisosteus  osseus  Linn.  .  . 
Ameiurus  lacustris  Wal.  .  . 
Aplodinolus  grunniens 

Raf 

Perca  flavescens  Mitch. .  .  . 
Stizostedion  vitreum  Mitch. 

Microplerus  salmoides  Lac. 

Micropterus  dolomieii  Lac. 
Hiodon  alosoides  Raf. .  .  .  . 

Hiodon  tergisus  LeS 

Schilbeodes  gyrinns  Mitch. 

Carpiodes  sp 

Esox  lucius  Linn 

Labidesthes  sicculus  Cope. 
Eucalia  inconstans  Kirt. .  . 
Coregonus  clupeiformis 

Mitch 

Ambloplites  rupestris  Raf. 
Eucrangonyx  gracilis 

Smith 

Lymnaea  lanceata  Gld. .  .  . 
Argyrosomus  prognalhus 

Smith 

Lota  maculosa  LeS 

Crislivotner  namavcush 

Wal '. 

Argyrosomus  hoyi  Gill 

(MSS) _ 

Pontoporeia  hoyi  Smith. .  . 

Mysis  relicta  Loven 

Argyrosomus  nigripinnis 

Gill 

Triglopsis  thorn psoni  Gir . . 


Depth  in  Meters 


Literature 


(75,  81) 
(7S,P.iS) 
(7S,P-i5) 
(81,  84) 
(81,  84) 

(84) 
(81,  84) 
(81) 

(81) 


(81,  84) 
(81,  84) 
(81,  84) 
(81) 
(81,  84) 
(81) 
(75:  81) 

(75,  81) 
(81) 

(80) 
(75,  80) 

(75) 
(75,  81) 

(75,  81) 

(75,  81) 
(82,  75) 
(82,  75) 

(75,  81) 
(75,  81) 


CHAPTER  VI 

ANIMAL  COMMUNITIES  OF  STREAMS 

I.    Introduction 

The  conditions  in  streams  from  headwaters  to  mouth  have  many 
features  in  common  with  lakes,  like  Lake  Michigan.  It  is  therefore 
appropriate  that  they  follow  the  discussion  of  such  a  lake.  The  streams 
belong  to  two  drainage  systems — the  Mississippi  and  the  Saint  Lawrence. 
All  are  tributary  either  to  Lake  Michigan  or  to  the  Illinois  River.  The 
principal  tributaries  of  the  lake  near  Chicago  are  the  Chicago  River,  the 
Calumet  River,  Trail  Creek,  the  Galien  River,  the  St.  Jospeh  River, 
and  the  Black  River.  The  principal  tributaries  of  the  Illinois  River, 
with  which  we  are  concerned,  are  the  Fox  River,  the  DesPlaines  River, 
the  DuPage  River,  the  Kankakee  River,  Salt  Creek  (III.),  Hickory  Creek. 

The  factors  of  greatest  importance  in  governing  the  distribution  of 
animals  in  streams  are  current  and  kind  of  bottom.  They  influence 
carbon  dioxide,  light,  oxj^gen  content,  vegetation,  etc. 

These  factors  are  controlled  by  age  (physiographic),  length  of  stream, 
and  elevation  of  source  above  the  mouth,  all  of  which  are  physiographic. 
The  typical  stream  begins  as  a  gully  and  works  its  way  into  the  land 
(Fig.  68,  p.  112).  The  importance  of  some  of  the  factors  is  greater  in 
some  stream  stages  than  in  others.  For  example,  in  the  younger  stages 
(a)  material  eroded,  (b)  relation  to  ground  water,  and  (c)  slope  of  stream 
bed  play  a  more  important  role  than  they  do  in  later  stages. 

II.  Communities  of  Streams 
I.  classification 
The  classification  of  stream  communities  is  based  upon  physio- 
graphic history  and  physiographic  conditions.  In  the  early  stages  of 
stream  development  there  are  two  tv^pes  to  be  distinguished:  (a)  the 
communities  of  intermittent  streams,  and  (b)  spring-fed  streams.  As 
soon  as  the  intermittent  stream  cuts  below  the  ground-water  level, 
it  becomes  much  like  the  spring-fed  stream.  Permanent  streams  are 
divided  into  brooks,  swift  and  moderate,  and  rivers,  sluggish  and  moder- 
ate, with  communities  named  accordingly.  We  undertake  a  discussion, 
first,  of  the  history  of  the  communities  of  streams  developing  in  materials 

86 


INTERMITTENT  STREAMS 


87 


easily  weathered  and  eroded,  containing  bowlders,  gravel,  and  occasional 
strata  of  hard  rock. 

2.      THE   INTERMITTENT   STREAM   COMMUNITIES 

(Stations  4-8;  Tables  XVII,  XVIII) 

There    are    two    types    of    these — intermittent    rapids    and    pool 
communities. 


An  Intermittent  Stream 

Fig.  24. — The  young  stream  at  Glencoe  in  spring  at  high  water,  showing  the 
leaf-barren  trees. 

Fig.  25. — The  same  in  summer,  showing  the  stream  entirely  drj-. 

a)  Temporary  rapids  consocies  (Figs.  24,  25). — Small  gullies  in 
which  water  runs  only  when  it  is  raining  do  not  have  any  aquatic 
residents.  As  soon  as  such  a  gully  has  cut  a  channel  deep  enough  to 
stand  below  ground-water  level  during  a  few  days  or  weeks  of  the  rainy 
season,  aquatic  insects  make  their  appearance.  The  species  which  is 
usually  found  in  the  smallest  trickle  of  water  is  the  larva  of  the  black  fly, 
Simulitim  (Figs.  27-32).  As  the  stream  grows  a  little  larger,  and  per- 
haps even  at  such  a  young  stage  also,  we  sometimes  find  the  nymphs 


88 


ANIMAL  COMMUNITIES  OF  STREAMS 


of  May-flies.  Such  streams  have,  however,  no  permanent  aquatic  resi- 
dents. These  aquatic  forms  are  not  aquatic  during  their  entire  lives. 
They  require  water  only  during  their  early  stages.  If  the  water  is 
running  at  the  time  the  female  is  ready"  to  deposit  eggs  and  if  she  is 
properly  stimulated  by  the  conditions,  she  deposits  them  without  regard 
to  future  conditions.  If  the  wet  weather  continues  long  enough,  the 
larvae  will  mature  and  the  other  adults  will  appear,  otherwise  they  die. 
This  type  of  animals  continues  after  the  stream  becomes  large  enough 


Stream  Communities 

Fig.  26. — The  pupal  case  of  one  of  the  caddis-worms  (Rhyacopliila)  from  the 
rapids  of  the  temporary  stream  at  Glencoe;   enlarged  as  indicated  (original). 

Fig.  27. — The  larva  of  the  black  fly  {Simiiliuni);  about  15  times  natural  size 
(after  Lugger) . 

Fig.  28. — Pupa  of  the  same  (after  Lugger). 

Fig.  29. — Pupa  of  the  same  in  the  pupal  case  (original). 

to  have  permanent  pools.  At  such  a  stage  the  number  of  species  is 
increased,  but  no  two  collections  are  alike  (see  Table  XVII).  Clinging 
to  the  upper  surface  of  the  stones  are  black-fly  larvae,  caddis-w^orms 
(Rhyacophilidae)  (Fig.  26);  under  stones,  May-fly  nymphs,  those  col- 
lected as  different  times  often  belonging  to  different  species.  On  some 
occasions  there  are  great  numbers  of  unidentifiable  dipterous  larvae 
and  caddis-worms  without  gills  or  cases.  Such  a  stream  may  possess 
any  or  all  of  these  on  one  occasion,  and  none  or  only  a  few  of  them  on 
another. 


INTERMITTENT  STREAMS 


89 


Fig.  30. — The  eggs  of  the  black  fly,  about  15  times  natural  size  (from  Williston 
after  Lugger).     Fig.  31. — Side  view  of  the  adult  fly  (from  Williston  after  Lugger). 
Fig.  32.— The  same  from  above  (from  Williston  after  Lugger). 


90  ANIMAL  COMMUNITIES  OF  STREAMS 

b)  Temporary  pool  consocies.— As  a  ^-oung  stream  grows  deeper  it 
often  reaches  some  depression  or  marsh  at  its  headwaters  of  which  it 
forms  the  outlet  in  the  early  spring.  It  is  now  permanent  for  a  longer 
period  each  season  of  normal  rainfall,  and  small  pools  usually  alternate 
with  the  rapids  just  described.  In  these  pools  aquatic  insects,  crus- 
taceans, and  snails  which  belong  primarily  to  stagnant  ponds  make 
their  appearance.  The  first  resident  species  are  the  crayfishes.  They 
are  found  in  the  pools  in  the  early  spring  when  the  water  is  high.  The 
drying  of  the  stream  calls  forth  behavior  suited  to  the  conditions, 
and  in  summer  their  burrows  are  common  in  the  stream  bed.  They 
come  out  at  night  and  are  preyed  upon  by  raccoons,  the  tracks  of  which 
are  commonly  seen. 

c)  The  horned  dace,  or  permanent  pool  communities. — The  first  per- 
manent parts  are  permanent  pools.  In  these,  conditions  such  as  current, 
sediment,  oxygen  content,  etc.,  are  intermittent  or  spasmodic.  The 
current  in  the  rapids  is  distinctly  spasmodic  and  conditions  in  these 
rapids  are  similar  to  those  in  the  stream  before  even  temporary  pools 
were  developed.  Streams  with  permanent  pools  are  represented  in  the 
Chicago  region  by  many  which  enter  the  lake  where  high  bluffs  are 
present.  County  Line  Creek  (Figs.  24,  25)  has  been  studied  as  an  illus- 
tration of  this  type  (Table  XVII). 

The  larger  pools  possess  a  practically  permanent  fauna.  The  char- 
acteristic forms  are  the  crayfishes  {Cambarus  virilis  and  propinquus). 
The  young  are  to  be  found  in  the  pools  at  all  seasons  of  the  year.  Water- 
striders,  back-swimmers,  and  water-boatmen  are  common.  Occasionally 
one  finds  dragon-fly  nymphs  (Aeshna  constricta  and  Cordulegaster  obli- 
quus),  dytiscid  beetles  (Hydroporus  and  Agabus),  crane-fly  larvae,  the 
brook  amphipod  {Gammarus  fasciatus) ,  and  the  brook  mores  of  the  sow- 
bug  {Asellus  communis)  (Fig.  55,  p.  98).  These  are  common  among  the 
lodged  leaves.     They  move  against  water  current. 

The  species  of  fish  (Table  XVIII)  which  is  most  commonly  found 
in  the  smallest  streams  (92)  and  nearest  the  headwaters  of  the  larger 
streams  is  the  horned  dace  or  creek  chub  {Semotilus  atromaculatus)  (Figs. 
33,  34).  It  possesses  certain  noteworthy  physiological  characters.  Like 
many  other  species  of  fish,  it  goes  farthest  upstream  for  breeding  (50). 
Its  nest  is  made  of  pebbles.  Often  after  the  breeding  season  is  over,  and 
the  adults  have  gone  downstream,  the  water  lowers  so  that  young  fishes 
are  left  in  large  numbers  in  small  drying  pools.  Here  they  swim  about, 
with  their  mouths  at  the  top  of  the  water,  which  is  constantly  being 
stirred  up  by  the  many  tails,  and  which  often  contains  much  blackened, 


INTERMITTENT  STREAMS 


91 


oxygen-consuming  excreta  and  decaying  plant  materials.  This  would 
cause  death  to  less  hardy  fishes.  AUee  (53)  found  very  little  oxygen  in 
the  waters  of  such  pools.  As  it  is,  the  pools  often  dry  up,  and  the  fish 
die.  The  second  fish  to  enter  a  small  stream  appears  to  have  many  of 
the  characters  of  the  first.  It  is  usually  the  red-bellied  dace  (Chrosomus 
erythrogaster),  which  breeds  on  sandy  or  gravelly  bottom  (93)  but  toler- 
ates standing  water,  being  found  also  in  some  of  the  stagnant  ponds  at  the 
south  end  of  Lake  Michigan.  In  some  streams,  the  black-nosed  dace 
(Rhinichthys  atronasus)  (Fig.  35)  is  second  from  the  source.  These  fishes 
go  against  the  current,  but  avoid  the  places  where  it  is  most  violent. 


Breedixg  Habits  of  a  Pioneer  Stream  Fish 

Fig.  ^^. — Showing,  in  longitudinal  section,  the  nest  of  a  horned  dace  (Semoliliis 
alromacitlatiis),  with  male  and  female  fish  in  the  nest.  The  stream  flows  in  the  direc- 
tion indicated  by  the  arrow  at  the  upper  left-hand  corner  of  the  picture;  |  natural 
size  (after  Reighard) . 

Fig.  34. — Male  and  female  horned  dace  during  the  spawning  act.  Each  time 
the  male  clasps  the  female  she  deposits  25  to  50  eggs  in  the  nest.  Note  pearl  organs  on 
the  head  of  the  male  (after  Reighard) . 


This  one  also  breeds  on  gravel  bottom,  and  can  withstand  the  stagnant 
conditions  of  the  summer  pools. 

As  the  stream  lowers  its  bed,  this  type  of  formation  passes  gradually 
into  a  later  one.  The  beginning  of  the  succeeding  formation  is  heralded 
by  the  coming  of  the  Johnny  darter  (Boleosoma  nigrum),  the  common 
sucker  {Catostomns  conimersonii)  (Fig.  36),  and  the  blunt-nosed  minnow 
(Pimephales  notatus)  (Fig.  37)  (79). 

d)  Characters  of  the  communities. — The  intermittent-stream  com- 
munities are  made  up  of  animals  which  are  dependent  upon  water 
during  only  a  part  of  their  lives  and  which  possess  a  means  of  attach- 
ment and  move  against  current  (94)  (positive  rheotaxis).  The  pool 
communities   are   made   up   of   animals   tolerating   great  extremes  of 


92 


ANIMAL  COMMUNITIES  OF  STREAMS 


conditions  and  being  also  positively  rheotactic.  The  fish  are  able  to 
meet  the  current  and  to  withstand  the  conditions  of  the  stagnant  pools. 
The  crayfishes  live  in  the  water  in   the   spring   and   burrow   in    the 


35 


.^.^m 


Pioneer  Stream  Fishes 

Fig.  35. — Black-nosed  dace  {Rhinichthys  atronasus)  (from  Forbes  and  Richardson) . 

Fig.  36. — Common  sucker  {Catostomiis  commersonii);  length  18  in.  (from  Meek 
and  Hildebrand  after  Forbes  and  Richardson). 

Fig.  37. — Blunt-nosed  minnow  (Pimephales  notakts);  length  2  to  3^  in.  (from 
Forbes  and  Richardson). 


dry  weather;  adults  of  the  aquatic  insects  creep  into  moist  places 
when  the  stream  dries.  Allee  (53)  has  found  that  isopods  are  positively 
rheotactic  and  that  they  can  be  acclimated  to  extreme  conditions. 


SWIFT  STREAMS  93 

3.       SPRING   BROOK   COMMUNITIES 

(Stations  10  and  11;  Table  XIX) 

In  glaciated  areas  many  of  the  streams  are  fed  by  springs  which 
have  not  been  produced  by  erosion,  but  are  the  result  of  porous  and 
impervious  layers  of  till  arranged  as  in  regions  possessing  artesian  wells. 
The  presence  or  absence  and  numbers  of  animals  in  a  spring  depend 
largely  upon  the  chemical  content  of  its  water.  Spring  waters  commonly 
have  insufficient  oxygen  to  support  animals  and  at  the  same  time  may 
contain  sufficient  nitrogen  and  carbon  dioxide  to  be  detrimental  if  not 
fatal  to  animals.  The  mineral  matter  in  solution  may  be  large  in 
quantity  and  in  some  cases  poisonous  also.  As  the  water  flows  away 
from  the  spring  it  becomes  aerated  and  diluted  with  surface  water  so 
that  the  animals  of  the  spring  brook  can  live  in  it.  Spring  consocies  differ 
in  different  springs  because  of  variations  in  the  character  of  the  water. 

In  an  area  where  there  are  springs,  they  are  usually  numerous. 
The  little  brooks  unite  to  form  larger  streams.  Typically,  such  streams 
may  not  be  larger  than  intermittent  streams,  but  a  nearly  constant 
flow  at  all  times  of  the  year  is  one  of  the  characteristic  conditions. 
Pools  and  rifiles  are  not  so  well  defined,  but  contain  some  small  fishes. 
The  watercress  grows  abundantly  at  the  sides  of  the  stream  and  affords 
a  lodging-place  for  aquatic  animals  not  furnished  so  abundantly  by 
young  streams  of  other  types.  The  water  is  colder  in  summer  and 
warmer  in  winter  than  in  other  streams. 

Spring  brook  associations. — ^x\mong  the  watercress  are  the  amphipods 
{Gammarus  fasciatus),  the  larvae  of  Simulium  attached  to  the  leaves, 
beetles,  dragon-fly  nymphs,  and  young  crayfishes.  Here  are  also  found 
occasional  snails  (Physa  gyrina).  The  species  of  the  cress  association 
are  nearly  all  found  under  stones  or  on  stones  in  the  riifies.  On  the 
stones  are  Simulium  larvae  and  Hydro  psyche  (95),  the  net-building 
caddis- worm  (Figs.  39,  40,  p.  96).  Under  the  stones  are  the  nymphs  of 
the  May-fly  {Baetis  and  Heptagenia),  the  larvae  of  flies  and  midges 
(Chironomus,  Dixa,  and  Tanypus),  the  brook  beetles  {Elmis  fastiditus) 
(Fig.  47,  p.  98),  and  occasional  amphipods  and  crayfishes. 

4.      THE    SWIFT-STREAM  COMMUNITIES 

As  the  spring  brooks  and  the  intermittent  streams  continue  to 
erode  their  beds,  they  increase  the  extent  of  their  drainage  systems  and 
become  larger  streams.  Springs  tend  to  disappear  in  connection  with 
the  spring  brook  and  the  intermittent  stream  reaches  the  ground-water 
level   and  becomes  permanent.     The  two  sets  of  conditions  converge 


94 


ANIMAL  COMMUNITIES  OF  STREAMS 


toward  the  larger  swift  stream  (Fig.  38).  While  the  conditions  in  these 
are  like  those  of  the  spring  brook,  the  watercress  is  absent  and  there  are 
few  rooted  plants.  Pools  and  riffles  are  well  developed  and  the  flow  of 
water  is  constant,  but  fluctuates  in  volume.  These  streams  differ  in 
size,  but  the  formation  mores  are  practically  the  same,  although  larger 
species  commonly  inhabit  the  larger  stream. 

a)  Pelagic  sub-formation  is  very  poorly  developed  in  the  smaller 
streams  and  will  be   discussed  in  connection  with  sluggish  streams. 


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Fig.  38. — The  permanent  swift  stream  showing  the  stones  in  the  rapids,  and  the 
stiller  places  below  (New  Lenox,  111.,  Gaugars  Station)  (original). 


b)  Hydropsyche  or  rapids  formations  (Stations  14,  15,  17,  19,  20,  21; 
Tables  XX,  XXI,  XXII). — These  are  usually  due  to  the  presence  of 
coarse  material  or  an  outcrop  of  rock.  They  are  tv-pical  in  streams  with 
large  bowlders  and  stones  of  all  sizes.  Here  current  is  probably  the 
controlling  factor.  In  these  streams,  we  find  the  best  expression  of  the 
riffle  formation,  which  we  have  seen  is  poorly  developed  in  the  smaller 
streams.  This  formation  includes  three  ecologically  equivalent  modes  of 
life,  each  meeting  the  current  in  a  different  way.     These  are  (i)  cHnging 


SWIFT  STREAMS  95 

to  stones  in  the  current,  (ii)  avoiding  the  current  by  creeping  under 
stones,  (iii)  self-maintenance  by  strong  swimming  powers. 

Upper  surface  of  stones  (stratum  i) :  Here  again  we  find  the  black-fly 
larvae,  particularly  in  the  smaller  streams.  They  are  provided  at  the 
posterior  end  of  the  body  with  a  sucker  surrounded  with  hooks  (Figs. 
27-32).  The  salivary  glands  are,  as  is  common  in  insects,  modified  into 
silk  glands  and  the  silk  is  of  such  a  nature  that  when  it  is  brought  into 
contact  with  a  stone  it  adheres.  The  animals  are  usually  found  attached 
to  the  rock  by  the  sucker,  with  the  head  downstream.  The  fans  are 
extended  and  serve  to  catch  diatoms  and  other  floating  algae.  If  for 
any  reason  the  sucker  gives  way,  the  animal  starts  to  float  downstream. 
If  the  mouth  can  be  brought  into  contact  with  a  stone,  the  silk  is  exuded 
and  the  animal  is  held  until  it  can  make  the  sucker  fast  again.  The 
pupae  of  this  fly  are  also  attached  to  the  stones.  They  are  surrounded 
with  a  cocoon.  We  have  removed  them  from  the  stream  and  have 
found  that  they  cannot  make  this  cocoon  in  the  absence  of  the  current, 
but  make  a  shapeless  tangle  instead.  The  adults  deposit  their  eggs  at  the 
sides  of  the  streams  (96). 

On  the  tops  of  stones  caddis-worms  {Hydropsyche  sp.)  usually  have 
cases  made  of  pebbles  stuck  together  with  silk  (Figs.  39,  40).  They  also 
have  a  net  for  catching  floating  food.  The  net  faces  the  current  (usually 
upstream)  (Fig.  40).  The  river  snail  {Goniobasis  livescens)  (Fig.  54)  is 
common  on  the  upper  surfaces  of  the  larger  rocks  and  is  distinguished 
by  a  strong  adhesive  foot.  These  snails  are  usually  headed  upstream. 
When  placed  in  a  long  piece  of  eave-trough  into  which  the  tap  water  was 
running  at  one  end,  they  nearly  all  made  their  way  to  the  upper  end 
within  a  short  time.  They  are  ecologically  equivalent  to  the  caddis-worms 
and  the  black-fly  larvae. 

Among  the  stones  (stratum  2) :  Of  the  animals  living  among  stones, 
the  darters  are  most  important.  Of  these  the  banded  darter  (Etheostoma 
zonale)  (Fig.  44),  the  fan-tailed  darter  (£.  flabellare),  and  the  rainbow 
darter  {E.  coeruleum)  (97)  (Fig.  45)  live  among  and  under  the  stones  or 
in  the  algae  which  cover  the  rocks  (especially  the  fantail).  With  them 
are  some  times,  found  the  Johnny  darter  {Boleosoma  nigrum),  the  black- 
sided  darter  {Hadropterus  aspro)  (Fig.  46),  and  the  small  bullhead  or 
stonecat  {Schilbeodes  exilis).  These  fish  are  all  positively  rheo tactic. 
They  apparently  orient  because  of  unequal  pressure  on  the  two  sides  of 
the  body  when  it  is  not  parallel  with  the  direction  of  the  current. 

Under  the  stones  (stratum  3):  There  are  many  more  forms  living 
under  and  among  the  stones  than  on  the  tops  of  them.     Here  are  the 


96 


ANIMAL  COMMUNITIES  OF  STREAMS 


May-fly  nymphs,  the  flattened  Heptageninae,  and  the  more  or  less  rounded 
Siphlurus  (95)  (Figs.  48,  49,  50),  evidently  succeeding  well  together. 
This  fact  makes  the  value  of  the  flattening  as  an  adaptation  appear  nil. 
There  are  also  the  larvae  of  midges  {Chironomus  sp.)  (98)  and  of  horse- 
flies (Tabanus)  (Figs.  51,  52).  The  adults  of  the  latter  deposit  their 
eggs  in  great  masses  on  the  tops  of  the  stones  which  protrude  from  the 
water.     The  stone-fly  nymphs,  similar  to   the   Heptageninae   May-fly 


Representative  Aquatic  Insects  of  a  Rapids  Community 

Fig.  39. — ^The  net  of  the  brook  caddis- worm  {Hydropsyche)  seen  from  the  front. 
Drawn  from  a  specimen  which  made  its  case  against  the  side  of  an  aquarium  (original). 

Fig.  40. — ^The  same  in  its  case  with  the  net  adjoining  the  opening  which  faces 
upstream  (original). 

Fig.  41. — The  larva  of  a  caddis-fly  {H el ico psyche)  with  a  case  made  from  pebbles, 
in  the  form  of  a  spiral;  2I  times  natural  size  (original). 

Figs.  42,  43. — The  water-penny  larva  of  the  brook,  beetle  (Parnidae)  seen  from 
above  and  below  (43);  2^  times  natural  size  (original). 


nymphs  in  form  and  appearance,  are  found  here  also.  Perhaps  the 
most  bizarre  of  all  are  the  water-pennies.  These  are  round  flat  objects 
adhering  to  the  under  sides  of  stones,  and  not  looking  like  animals  at 
all.  They  are  the  larvae  of  a  parnid  beetle  (Psephenus).  Figs.  42  and 
43  show  two  views  of  a  larva.  The  old  larval  back  becomes  the  cover 
for  the  pupa.  Tha  adults  live  under  the  stones  also  and  their  general 
appearance  is  like  that  of  the  parnid  in  Fig.  47.  Sessile  or  attached 
animals  are  common  in  the  brooks,  but  their  numbers  vary  greatly  from 


SWIFT  STREAMS 


97 


year  to  year.  On  one  occasion  the  surface  of  the  rocks  and  stones  in 
Thorn  Creek  was  almost  covered  with  sponge,  and  while  some  sponge  is 
always  to  be  found,  we  have  not  seen  it  so  abundant  again.     Polyzoa 


Representative  Fishes  of  a  Rapids  Community 
Fig.  44. — The  banded  darter  {Etheostoma  zonale);  length  2  in.  (from  Forbes). 
Fig.  45. — The  rainbow  darter  {Etheostoma  coeriileum);  length  2  in.  (from  Forbes). 
Fig.  46. — Black-sided  darter  {Hadropterus  aspro);  length  3-4  in.  (from  Forbes). 

are  usually  present  under  the  stones.     Such  animals  depend  upon  foods 
in  solution  and  small  floating  jylants  and  animals. 

In  addition  to  those  rapids  which  have  large  rocks,  are  those  in  which 
the  bottom  is  of  coarse  sand  and  gravel,  with  only  a  few  small  stones. 


98 


ANIMAL  COMMUNITIES  OF  STREAMS 


Representative  Animals  of  a  Rapids  Community 

Fig.  47. — An  adult  brook  beetle  {Parnidae);  twice  natural  size  (original). 

Figs.  48-50. — Different  views  of  the  nymph  and  adult  of  the  May-fly  {Siphlurus 
allcrnatus);  3I  times  natural  size  (after  Needham). 

Fig.  51. — The  eggs  of  a  tabanid  fly  taken  from  a  protruding  stone;  twice 
natural  size  (original).     Fig.  52. — Adult  fly. 

Fig.  53. — A  water-strider  {Rhagovelia  collar  is),  from  the  margin  of  the  swift 
brook  (New  Lenox,  Gaugars);  twice  natural  size. 

Fig.  54. — The  common  river  snail  (Goiiiobasis  livescens),  covered  with  calcium 
carbonate  secreted  by  algae;  natural  size  (original). 

Fig.  55. — An  intermittent  stream  sowbug  {Asellus  communis);  twice  natural 
size  (original). 


SWIFT  STREAMS  99 

Here  we  find  the  caddis- worm  {Helicopsyche)  (Fig.  41,  p.  96),  which  has  a 
spiral  case  made  of  sand  grains.  These  are  most  abundant  where  some 
sand  and  swift  current  are  both  found.  There  is  from  time  to  time  some 
vegetation  in  such  situations  and  on  it  we  find  the  brook  damsel-fly 
nymph  (Calopteryx  maculata),  the  adult  of  which  is  the  black-winged 
damsel-fly. 

Characters  of  the  formation:  The  swift-stream  formation  has  a 
striking  behavior  character,  namely,  strong  positive  rheotaxis.  Other 
physiological  characters,  such  as  the  toleration  of  only  low  temperatures 
and  high  oxygen  content,  and  the  necessity  for  current  for  the  successful 
carrying-on  of  their  building  operations,  are  probably  common  to  the 
animals.  So  far  as  the  fishes  of  the  rapids  are  known,  they  breed  on 
coarse  gravel  bottom  or  under  stones.  The  mores  of  the  formation  are, 
then,  current  resisting  and  current  requiring,  dependent  upon  large 
stones  or  rock  bottom  for  holdfast  and  building  materials. 

c)  Sandy  and  gravelly  bottom  formation  (pools)  (Stations  15-22; 
Tables  XVII-XXV). — The  pools  of  streams  with  characteristic  forma- 
tions are  usually  2  or  3  to  10  feet  deep,  depending  upon  the  size  of  the 
stream.  The  bottom  is  sand  or  coarse  gravel.  In  these  we  find  condi- 
tions very  different  from  those  in  the  rapids.  The  pools  are  the  home 
of  the  rock  bass  (Ambloplites  rupestris),  the  small-mouthed  black  bass 
(Micropterus  dolomieu),  the  sunfishes  (Lepomis  pallidus  and  megalotis), 
and  the  perch  (Perca  flavescens) ,  together  with  a  number  of  interesting 
small  fishes  whose  distribution  is  shown  in  Tables  XXI  and  XXII 
(79,  92). 

With  these  are  also  the  mussels  (91),  frequently  as  many  as  nine  or 
ten  species,  among  which  are  Lampsilis  luteola,  ventricosa,  and  liga- 
mentina,  the  little  Alasmidonta  calceola  (Figs.  57,  58),  and  Anodontoides 
ferussacianus  (Figs.  59,  60),  the  last-named  being  perhaps  the  most 
characteristic  of  them  all.  They  are  often  found  beneath  the  roots  of 
willows  along  the  sides  of  the  pools.  Mr.  Isely  found  that  mussels 
migrate  to  shallow  water  during  flood  time.  Mussels  are  dependent 
upon  fish  for  a  part  of  their  lives.  The  young  are  carried  by  the  adult 
until  ready  to  attach  to  the  body  of  the  fish  (99).  When  they  leave  the 
fish  they  are  able  to  take  care  of  themselves.  Burrowing  in  the  gravel 
are  bloodworms  (Chironomus  sp.)  (95,  98),  the  burrowing  dragon-fly 
nymph  (Gomphus  exilis),  a  burrowing  May-fly  (Fig.  64a,  p.  107),  a  caddis- 
worm,  and  occasionally  snails,  Campeloma  (Fig.  61  or  64c)  and  Pleuro- 
cera  (Fig.  64J).  There  are  a  few  plants  that  grow  on  the  sandy  bottom 
in  such  places,  and  among  these  one  finds  the  snail  (Amnicola  liniosa), 


AXIMAL  COMMUNITIES  OF  STREAMS 


Representatives  of  the  Pool  Community 

Fig.  56. — A  long-legged  spider  taken  from  a  stone  out  of  water  in  a  stream 
{Tetragnatha  grallaior);  twice  natural  size  (original).  Fig.  57. — Outside  of  shell  of  a 
small  mussel  from  Hickory  Creek  {Alasmidonta  calceola);  natural  size  (original). 
Fig.  58.— Inside  of  the  same.  Fig.  59. — Inside  of  shell  of  mussel  from  Hickory  Creek 
(Anodontoides  fenissacianus,  subspecies  subcylindraceus  Lea);  natural  size  (original). 
Fig.  60. — Outside  of  the  same.  Fig.  61. — ^A  snail  from  the  stiU  water  of  Thorn  Creek 
{CampeJoma  subsolidum);  natural  size  (original).  Fig.  62. — A  snail  from  the  still 
water  of  Hickory  Creek  (Planorbis  bicarinatus) ,  seen  from  the  left;  natural  size 
(original).     Fig.  63. — The  same  seen  from  the  right. 


SANDY  BOTTOMED  STREAMS  loi 

occasional  aquatic  insects,  and  hair-worms  {Gordius).  In  some  localities 
bivalved  mollusks  (Sphaeridae)  and  leeches  are  numerous. 

Under  primeval  conditions  beavers  are  associated  with  the  pool  for- 
mation. They  build  dams  which  contribute  to  the  deepening  of  the 
water  of  the  pools.  For  a  good  account  of  their  habits  see  citation  ggb. 
An  old  beaver  dam  is  supposed  to  have  turned  the  waters  of  the 
DesPlaines  out  of  the  Chicago  River  and  down  the  Chicago  outlet. 

Characters  of  the  formation :  The  mores  of  the  pool  formation  are  dis- 
tinctly those  of  partially  burying  the  body  just  beneath  the  surface  of 
the  fine  gravel  and  moving  against  the  current.  The  few  animals  that 
make  cases  usually  use  gravel  or  sand  grains.  A  single  caddis-worm 
makes  its  case  from  small  sticks  such  as  commonly  lodge  in  eddies. 
Some  of  the  fishes  breeding  in  these  situations  cover  their  eggs  (50). 
Some  fishes  orient  the  body  and  swim  upstream  as  a  result  of  seeing  the 
bottom  apparently  move  forward  below  as  the  fish  floats  down  (94). 
They  behave  the  same  if  put  into  a  trough  with  a  glass  bottom  and  the 
trough  drawn  forward.  Some  orient  also  when  their  bodies  rub  against 
the  bottom  when  floating  downstream. 

5.    the  communities  of  sandy  bottomed  streams  (shifting  bottom 

sub-formations) 
(Stations  22-26;  Table  XXIV) 

We  have  studied  the  upper  course  of  the  Black  River,  the  upper 
course  of  the  Calumet  River,  and  the  Deep  River,  and  two  or  three 
tributaries  of  Lake  Michigan  near  South  Haven.  The  kind  of  material 
eroded  is  of  the  greatest  importance  in  determining  the  mores  present  in 
a  stream.  The  streams  of  the  eastern  part  of  our  area  are  in  till  which 
is  sandy  and  their  bottoms  are  sandy.  This  material  is  always  slipping 
and  moving  downstream.  There  are  few  large  stones.  The  bottom  is 
not  suitable  for  animals.  The  swift-water  animals  are  almost  entirely 
absent.  The  forms  present  are  those  which  belong  to  moderately  swift 
water. 

Composition  and  subdivisions. — Such  streams  are  poorly  populated. 
Their  mores  resemble  those  of  the  formations  of  the  pools  of  streams 
eroding  coarse  material,  but  the  shifting  is  so  much  more  general  and  the 
species  found  so  different,  that  it  has  been  thought  wise  to  separate  the 
two.  In  the  Michigan  streams  there  are  in  summer  a  few  scattered 
plants,  which  support  a  considerable  number  of  insects;  some  of  the 
brook  beetles  (Parnidae)  are  found  attached  to  them.  The  logs  and 
roots  that  happen  to  be  in  the  water  are  important;   they  are  the  only 


I02  ANIMAL  COMMUNITIES  OF  STREAMS 

places  that  support  any  amount  of  life.  From  these  logs  I  have  taken 
hundreds  of  specimens  of  small  Parnidae,  and  with  them  predaceous 
diving  beetles  (Dytiscidae)  which  were  found  hiding  in  the  cracks,  also 
a  few  scattered  caddis- worms  (Hydropsyche) .  The  fauna  of  the  bottom 
is  made  up  of  burrowing  and  semi-burrowing  forms.  The  little  dytiscid 
(Hydroporus  mellitus  Lee.)  (99c)  is  characteristic:  it  has  the  habit  of 
burying  itself  in  the  sand.  The  bivalved  mollusks,  especially  mussels, 
are  present.  From  the  Deep  River  (upper  course)  we  have  taken 
nearly  a  dozen  species.  The  only  snail  found  is  a  burrowing  form  also. 
Animals  of  such  a  stream  are  subject  to  severe  conditions.  Many 
of  them  burrow.  The  substratum  is  very  unstable  and  the  logs  and 
parts  of  trees  to  which  many  of  them  are  attached  are  free  to  float  down- 
stream with  every  flood.  We  know  nothing  of  the  reactions  of  these 
animals  to  various  stimuli.  They  are  distinctly  subjects  for  investi- 
gation. 

6.      THE   SLUGGISH   STREAM   COMMUNITIES 

(Stations  19,  27,  28,  and  29;    Tables  XVII,  XVIII,  XX-XXV) 

There  are  several  phases  or  types  of  sluggish  stream  formations. 
The  most  important  of  these  are  the  sluggish  or  base-level  creek,  the 
sluggish  river,  and  the  drowned  river.  These  are  all  illustrated  in  the 
Chicago  area. 

The  sluggish  creek  type  is  illustrated  by  the  west  branch  of  the 
DuPage  River  and  its  tributaries;  the  upper  course  of  the  west  branch 
of  Hickory  Creek,  Dune  Creek,  some  parts  of  the  Little  Calumet  south 
of  Millers,  and  the  Kankakee  and  some  of  its  tributaries. 

The  sluggish  rivers  are  the  Upper  Fox,  the  lower  St.  Joseph,  the 
Grand  Calumet,  the  lower  Galien,  the  lower  Black,  and  others.  These 
constitute  a  group  of  streams  representative  of  the  sluggish  type  about 
the  Great  Lakes. 

a)  Sluggish  creek  sub-formations  (Stations  16,  18). — The  west  branch 
of  Hickory  Creek  has  been  studied  in  a  cursory  manner.  The  fish  are 
a  strange  mixture  of  semi-temporary  stream  and  pond  forms.  The  black 
bullhead  (Ameiurus  melas)  (79)  is  probably  the  most  characteristic  fish. 
The  golden  shiner  (Abramis  crysoleucas)  and  sunfish  {Lepomis  cyanellus) 
are  also  found. 

Baker  (100)  studied  the  upper  portion  of  the  east-north  Chicago 
River.  He  recorded  the  same  species  of  Mollusca  as  were  taken  in  the 
upper  part  of  Hickory  Creek.  He  records  also  the  black  bullhead.  The 
insects  which  he  mentions  are  those  commonly  found  in  ponds.      This 


SLUGGISH  STREAMS  103 

community  is  distinctly  of  the  pond  type  in  its  general  mores.  Stagna- 
tion and  low  oxygen  content  and  the  partial  drying  of  the  stream  are 
tolerated  by  all  the  residents. 

b)  Sluggish  river  formations. — The  conditions  in  sluggish  rivers  are 
different  from  those  in  smaller  swift  streams  in  many  respects.  The 
bottom  is  for  the  most  part  of  fine  materials;  there  are  no  rocks.  The 
difference  between  pools  and  rapids  no  longer  exists.  The  river  is  a 
gently  flowing  mass  with  relatively  little  distinction  as  to  different  parts. 
The  margins  of  such  streams  are  lined  in  summer  with  typical  rooted 
and  holdfast  aquatic  plants.  The  small  bays  and  out-of-the-way  spots, 
out  of  the  current,  support  bulrushes  and  sometimes  cattails.  We  can 
distinguish  several  formations  in  the  Fox  River:  (i)  The  pelagic  forma- 
tion, (2)  the  formation  of  sand  and  silt  bottom  (association  of  sandy 
bottom  where  the  current  drags  in  midstream  or  beats  against  the 
shore;  association  of  silt  bottom  where  least  current  is  present),  and 
(3)  the  formation  of  the  zone  of  vegetation. 

Pelagic  formation:  This  is  well  developed  in  the  larger  rivers,  e.g., 
the  Illinois  River  (77).  While  the  Illinois  no  doubt  differs  from  the  Fox 
in  many  respects,  doubtless  the  general  features  are  much  the  same. 
It  does  not  differ  greatly  from  that  of  Lake  Michigan. 

Burrowing  May-fly  or  sand  and  silt  bottom  formations:  On  the 
bottom  in  ten  feet  of  water  we  have  found  mussels  (Anodonta  grandis 
and  Quadrula  undulata),  the  snail  (Goniobasis  Uvescens),  bloodworms 
(Chironomidae),  green  midge  larvae  (Chironomidae).  On  the  old  mussel 
shells  were  large  colonies  of  the  bryozoan  Plumatella  and  occasional 
caddis- worms  (Hydropsyche)  (Figs.  39,  40,  p.  96).  On  sandy  bottom, 
conditions  near  the  margin  are  similar  to  those  on  the  bottom.  We 
find  here  also  an  occasional  snail  (Goniobasis,  Pleurocera,  and  Campe- 
loma),  the  midge  larvae  and  bloodworms,  occasional  burrowing  May- 
fly nymphs,  and  a  number  of  mussels  {Unio  gibbosus  and  Quadrula 
rubiginosa  being  the  most  characteristic).  There  is  also  an  occasional 
specimen  of  the  long-legged  dragon-fly  nymph  (Macromia  taeniolata)  and 
the  black-sided  darter.  A  considerable  number  of  these  species  occur 
in  the  stillest  pools  of  Hickory  Creek,  indicating  the  types  that  will 
dominate  later.  Silt  is  often  found  in  particular  spots.  The  most 
characteristic  animals  in  this  are  the  large  mussel  {Quadrula  undulata), 
the  burrowing  May-fly  nymph  (Hexagenia  sp.),  and  the  bloodworms 
(Chironomidae).  There  are  also  the  worms  (Annelida)  which  burrow  in 
the  mud  and  protrude  their  anterior  ends,  often  also  the  common 
mussel  (Lampsilis  luteola),  the  Sphaeridae,  and  the  mud  leech  (Haemopis 


I04  ANIMAL  COMMUNITIES  OF  STREAMS 

grandis).  All  of  the  animals  of  the  silt  formation  burrow  and  prob- 
ably require  little  oxygen. 

Planorbis  bicarinatus  formation,  or  formation  of  the  vegetation: 
Here  we  have  for  the  first  time  the  conditions  which  we  find  in  ponds — 
.  a  dense  rooted  vegetation.  With  such  a  growth  of  vegetation  we  have 
a  very  different  fauna:  a  large  number  of  aquatic  insects  and  pulmonate 
(lunged)  snails.  Of  these  there  are  a  considerable  number  of  species 
which  must  come  to  the  surface  of  air,  both  in  the  adult  and  the  young 
stages.  The  most  important  of  these  are  the  bugs:  water  scorpions 
{Ranatra  fused) ,  the  creeping  water-bugs  (Pelocoris  femoraius) ,  the  small 
water-bug  {Zaitha  fluminea) ,  the  water-boatmen  {Corixa  sp.),  the  still- 
water  brook  beetles  or  parnids  {Elmis  quadrinotatus),  several  species 
of  predaceous  diving  beetles  {Dytiscidae)  (99c),  and  water  scavengers 
{Hydrophilidae).  The  pulmonate  snails  are  Physa  Integra,  Planorbis 
bicarinatus  (Figs.  62,  63),  and  often  species  of  Lymnaea. 

Where  the  bottom  is  not  too  soft  we  often  find  numbers  of  viviparous 
snails  (Campeloma)  and  an  occasional  mussel  (Anodonta  grandis).  The 
crustaceans  are  distinctly  clear- water  forms:  the  crayfish  (Cambarus 
propinquus)  (loi),  the  amphipod  (Hyalella  knickerboekeri) ,  and  the 
brook  amphipod  {Gammarus  faseiatus)  (102). 

The  gilled  aquatic  insects  are  the  May-fly  nymphs  {Caenis  and 
Callibaetis  sp.)  and  the  damsel-fly  nymphs  {Isehnura  verticalis)  and 
dragon-fly  nymphs  (Aesehnidae  and  Libellulidae) .  To  practically  all  of 
these  the  vegetation  is  necessary  as  a  resting-place  or  clinging-place,  or  a 
place  to  enable  them  to  creep  to  the  surface  to  shed  the  larval  skin  and 
become  adult. 

Variations  of  the  formation:  The  Fox  is  fairly  representative  of 
base-level  rivers  beyond  the  reach  of  tide-water  except  perhaps  that  the 
presence  of  gravel  and  sand  in  this  stream  may  not  seem  fully  in  accord 
with  this  statement.  There  are,  as  has  been  noted,  rivers  near  Chicago 
in  which  these  conditions,  which  go  along  with  old  age  in  a  stream,  are 
still  more  marked.  The  lower  Deep  River  is  perhaps  a  good  example  of 
this.  It  is  very  sluggish  and  the  bottom  in  the  vicinity  of  Li\-erpool, 
Ind.,  is,  so  far  as  we  have  been  able  to  ascertain,  entirely  covered  with 
silt,  with  considerable  humus  mixed  with  it.  The  margins  are  peaty. 
The  Calumet  and  the  lower  Black  are  similar.  In  these,  sand  and 
gravel  areas,  and  animals  which  inhabit  them,  are  reduced  to  a  mini- 
mum and  the  silt  and  vegetation  associations  are  better  developed. 

Characters  of  the  formation:  The  vegetation  formation  is  distinct 
and  clearly  marked  off  from  all  others.     The  animals  are  dependent  upon 


EFFECTS  OF  DROUGHTS  AND  FLOODS  105 

the  vegetation  for  support.  The  adult  aquatic  insects  must  creep  to  the 
surface  of  the  water  to  renew  their  air.  The  forms  that  have  gills  are, 
at  least  many  of  them,  dependent  upon  the  vegetation  for  crawling  to 
the  surface  to  molt  the  old  skin.  The  crustaceans  are  forms  that  cling 
to  the  vegetation  and  the  snails  must  come  to  the  surface  for  air.  Doubt- 
less this  formation  should  be  divided  into  strata,  but  our  data  do  not 
justify  such  division. 

III.     Special  Stre.\m  Problems  (103,  92) 

The  first  special  problem  is  that  of  the  relations  of  animals  to  seasonal 
changes,  to  changes  in  volume  of  water,  amount  of  silt,  shifting  of  bottom 
materials,  and  the  seasonal  aspects  of  the  vegetation.  The  second  prob- 
lem of  streams  is  the  historic  or  genetic,  which  includes  the  phenomena  of 
the  origin  of  the  animals  of  the  stream,  their  mode  of  entrance,  and  the 
effect  of  rejuvenation,  drowning,  etc. 

I.      SEASONAL   CHANGES 

Streams  are  more  strikingly  affected  by  rainfall  and  drought  than  are 
any  other  of  the  aquatic  habitats.  In  extremely  dry  years  streams  dry 
up  in  the  rapids  where  they  have  perhaps  not  been  dry  for  a  century. 
Floods  change  all  the  landmarks  of  the  stream  bottom  and  often  scatter 
the  animals  of  the  stream  over  the  flood-plain. 

a)  Floods. — We  found  at  the  side  of  the  high  bank  of  the  stream 
where  the  water  is  quiet  at  low  water,  the  Johnny  darter  (Boleosoma 
nigrum),  the  little  pickerel  (Esox  vermiculatus) ,  the  tadpole  cat  {Schil- 
beodes  gyrinus),  the  crayfish  (Cambarus  virilis),  and  an  occasional 
Hydropsyche.  Here  were  also  an  occasional  sphaerid  mollusk  and  one 
or  two  leeches. 

Caught  in  a  mass  of  driftwood  behind  the  roots  of  a  tree  were  case- 
bearing  caddis-worms  {Phryganeidae),  the  black-winged  damsel-fly 
nymph  {Calopteryx  maculata),  the  larvae  of  the  black  fly  {Similium  sp.), 
and  two  species  of  May-fly  nymphs  (one  Heptageninae).  The  last  two 
belong  to  the  swift  water,  the  others  to  the  still  water  or  the  pools. 
During  floods  the  still-water  fauna  and  the  swift-water  fauna  become 
mixed  in  the  still  places. 

At  the  time  of  our  study  there  was  a  growth  of  rank  weeds  on  the 
flood-plain.  While  the  stream  had  been  swollen  for  a  long  period  and 
had  stood  higher  than  at  the  time  of  observation,  little  or  no  invasion 
of  these  weeds  by  aquatic  animals  had  occurred.  Animals  evidently 
react  negatively  to  such  bottom  and  vegetation. 


io6 


ANIMAL  COMMUNITIES  OF  STREAMS 


We  have  had  but  little  opportunity  to  study  the  swift-water  forma- 
tion during  floods,  though  some  of  the  riffles  in  Butterfield  Creek  have 
been  studied  when  the  stream  was  bank  full,  but  no  marked  changes 
were  noted.  It  is  obvious  that  the  extreme  floods  which  move  large 
stones  crush  large  numbers  of  swift-water  animals. 

b)  Droughts. — There  was  an  unusual  drought  in  the  autumn  of  1908. 
The  data  on  the  distribution  of  fishes  in  Glencoe  Brook  and  County 
Line  Creek  were  collected  before  this  date  (Fig.  67,  p.  iii).  Table  XVI 
shows  the  arrangement  after  the  drought. 

TABLE  XVI 

Showing  the  Effect  of  Drought  on  Fishes 
The  localities  i,  2,  3,  4  are  indicated  on  the  maps  of  the  North-Shore  Streams 
(Fig.  67,  p.  III).    P=before  drought.     *P  =  after  drought. 


Name  of  Stream  and  Common 
Name  of  Fish 

Scientific  Name 

I 

2 

3 

4 

P 

P 

County  Line  Creek 

Horned  dace 

Semotilus  atromacidalus . .  . 
Rhinichthys  atronasus .  .  .  . 

P 

*P 
P 

*P 

*P 

Common  sucker 

*P 

County  Line  Creek  was  entirely  dry  except  the  pool  nearest  its 
mouth  in  September,  1908.  This  is  locality  4  in  Fig.  67,  p.  iii. 
The  following  spring  was  one  of  normal  rainfall.  The  fish  proceeded 
upstream  a  distance  of  only  three  rods.  This  partially  restored  the  usual 
arrangement.  If  this  represents  the  rate,  the  fish  proceed  upstream 
slowly.     Glencoe  Brook  has  not  recovered  its  fish. 

As  evidence  of  upstream  migration  of  Mollusca,  the  following  seems 
to  be  important.  Frequent  examination  of  a  section  of  the  North 
Branch  of  the  Chicago  River  at  Edgebrook,  between  1903  and  1907, 
showed  that  Pleurocera  elevatum  and  Campeloma  occur  in  this  stream. 
P/ewrocera  was  not  found  during  this  period  (ending  November,  1907) 
above  a  certain  point.  Campeloma  was  found  only  sparingly  above 
this  point.  The  spring  of  1908  was  one  of  heavy  rainfall  and  the 
streams  were  in  flood  from  April  to  June.  On  July  6  the  snail 
Pleurocera  was  found  in  numbers  one-fourth  of  a  mile  farther  up- 
stream than  formerly.  Campeloma  had  gone  nearly  as  far.  The  sea- 
son from  November  to  April  was  not  different  from  other  seasons 
and  there  is  no  reason  to  assume  that  the  migration  began  before  the 
spring  floods.     If  this  is  true  the  snails  could  make  their  way  toward 


EFFECTS  OF  DROUGHTS  AND  FLOODS 


107 


the  headwaters  at  the  rate  of  at  least  a  mile  per  year,  if  they  were  intro- 
duced into  a  large  stream.  This  must  be  a  response  to  both  water 
pressure  and  current.  The  small  value  of  such  single  observations  is 
recognized  but  they  are  presented  here  because  the  opportunity  to  secure 
such  data  is  small.  In  this  river  there  are  also  notable  relations  between 
especially  dry  seasons  and  the  distribution  of  other  animals.  The 
season  in  which  the  riffles  were  dry  (October  31,  1907)  the  pools  presented 


The  Transverse  Distribution  of  Stream  Animals 

Fig.  64. — Shows  the  form  of  bottom  and  size  of  bottom  materials  in  a  cross- 
section  of  the  North  Branch  of  the  Chicago  River,     a-d,  natural  size  (original). 

a,  a  burrowing  May-fly  nymph  {Hexagenia  sp.). 

b,  small  bivalve  {Sphaeriunt  stamineum) ,  two  individuals,  two  views. 

c,  viviparous  snail  {Campeloma  integrum),  seen  from  two  sides. 

d,  the  long  river  snail,  young  and  full  grown  {Pleurocera  eJevatiim). 
Fig.  65. — Cross-section  of  the  stream  with  reference  to  a  curve. 

an  unusual  aspect.  The  standing  pools  were  choked  with  water-net. 
The  minuter  forms,  such  as  protozoa  and  fiatworms,  were  present  in  the 
greatest  profusion.  Hydra  was  abundant.  All  this  is  in  marked  con- 
trast to  the  conditions  which  one  finds  when  the  stream  is  running. 

The  season  following  the  dry  riflles,  we  found  small  Hydropsycke 
larvae,  and  a  few  young  stone-fly  nymphs.  The  only  forms  present  were 
those  that  could  be  introduced  by  terrestrial,  egg-laying  females. 


Io8  ANIMAL  COMMUNITIES  OF  STREAMS 

In  the  autumn  of  1906  Professor  Child  found  that  the  May- fly  and 
stone-fly  nymphs  were  not  present  in  the  riffles  but  were  present  in  the 
moderately  swift  and  more  quiet  parts  below.  The  spring  of  1906  was 
a  dry  spring  and  the  females  probably  laid  their  eggs  in  the  moderately 
swift  instead  of  the  preferred  swift  water.  The  distribution  is  deter- 
mined by  the  conditions  at  the  time  of  egg  laying. 

We  note  that  even  in  the  larger  streams  the  weather  conditions 
affect  the  presence  and  absence  and  abundance  of  animals.  The  mores, 
however,  remain  essentially  the  same. 

2.      TRANSVERSE    STUDIES 

Cross-section  studies  of  streams  are  of  interest  as  showing  a  hori- 
zontal arrangement  of  forms  belonging  properly  to  different  formations. 
This  is  best  illustrated  in  the  cross-sections  of  curves  where  there  is  a 
horizontal  gradation  of  current  and  in  the  size  of  material  of  the  bed. 
Figs.  64  and  65  illustrate  this.  The  burrowing  May-fly  nymph,  belonging 
to  the  silt,  is  in  the  finest  materials  of  the  inside  of  the  curve;  passing 
toward  the  center  of  the  stream  we  next  encounter  the  sphaerid  {Sphae- 
rium)  and  a  little  farther  in  the  snail  (Campeloma  integrum) ,  with  it  often 
mussels  {Anodontoides  ferussacianus);  and  still  farther  into  the  stream 
we  find,  clinging  to  the  larger  stones,  the  long  snail  (Pleurocera  elevatum). 
While  depth  of  water  may  be  a  factor  here,  the  size  of  bottom  material 
is  of  first  importance. 

3.      LONGITUDINAL   STUDIES 

(Figs.  66,  67,  68,  69) 

If  one  passes  from  the  headwaters  of  a  stream  to  its  mouth,  he  will 
usually  find  either  the  spring  brook  formation  or  the  intermittent 
formation  in  the  upper  course,  the  swift-water  formations  in  the  middle 
course,  and  the  sluggish  stream  or  river  formations  in  the  lower  course. 
There  are  very  numerous  variations  of  this  and  several  of  them  deserve 
comment.  Large  streams  with  a  large  drainage  area  and  much  sedi- 
ment, and  with  much  of  the  upper  part  in  a  young  stage,  are  subjected 
to  many  changes  in  the  lower  courses,  such  as  silting-up  at  the  end  of  the 
flood  periods  and  washing  out  later.  This  often  prevents  the  development 
of  the  vegetation  formation  and  favors  the  shifting  sand  and  gravel  formations . 

a)  Rejuvenation,  ponding,  and  retarding  of  erosion. — Streams  are 
often  dammed  by  some  obstruction  in  their  mid  course,  or  erosion  is 
checked  at  a  point  by  a  hard  stratum,  or  the  stream  which  has  reached 
base-level  is  rejuvenated  by  a  lowering  of  the  water  level  at  the  mouth. 


LONGITUDINAL  STUDIES 


109 


The  obstruction  of  the  hard  layer  encountered  always  produces  local 
swift  water.  Above  this  the  water  may  be  sluggish  and  the  area  reduced 
to  the  general  level  of  the  obstruction.  In  the  case  of  rejuvenation  the 
head  of  erosion  proceeds  upstream ;  the  part  of  the  stream  above  the  point 
to  which  erosion  has  reached  is  sluggish  and  is  sometimes  called  the  pre- 
erosion  stream. 

Of  the  rivers  and  creeks  which  we  have  considered,  nearly  all  the 
larger  ones  are  sluggish  or  pre-erosion  in  their  upper  courses.  This  is 
true  of  the  DesPlaines,  which  is  held  in  this  condition  largely  by  rock 
at  Riverside.  Hickory  Creek  (Fig.  66)  is  also  of  this  type,  the  head  of 
erosion  being  at  Marley.  In  passing  from  source  to  mouth  of  such  a 
stream  we  find  formations  arranged  as  follows:  In  the  upper  sluggish 
courses  of  all  the  streams  mentioned  we  find  (i)  sluggish  creek  or 
river  formations,  (2)  chiefly  swift-water  formation's  below  the  sluggish, 
(3)  chiefly  gravel  bottom  formations  below  the  swift-water  formation. 


.^ 


// 


Fig.  66.— Diagrammatic  profile  of  Hickory  Creek:  A,  source;  5,  mouth;  C,  head 
of  erosion;  D,  rock  outcrop.  The  figures  below  refer  to  the  columns  in  Table  XXI 
and  represent  parts  from  which  fish  were  collected. 

and  (4)  typical  sluggish  river  formations  farthest  downstream  where 
the  vegetation,  silt,  and  sand  formations  are  arranged  much  as  in 
the  Fox  River. 

Tables  XVIII,  XXI,  and  XXII  and  Figs.  67-69  show  the  longi- 
tudinal distribution  of  fishes  in  six  streams.  A  few  moments'  study  and 
comparison  of  these  tables  will  make  the  following  facts  evident: 

a)  The  only  species  in  the  youngest  stream  of  the  North  Shore 
series  is  at  the  headwaters  of  all  the  others. 

b)  The  species  found  in  County  Line  Creek  are  found  in  the  same 
order  in  the  upper  courses  of  Pettibone  Creek  and  Bull  Creek;  additional 
species  are  found  farther  downstream  in  the  larger  streams. 

c)  The  same  species  are  at  the  headwaters  of  Thorn-Butterfield  and 
Hickory  creeks  and  in  the  upper  courses  of  the  North  Shore  streams. 
Other  species  are  with  them.  The  species  of  the  North  Shore  streams 
are   crowded   together   in  these  large  streams  which  have  permanent 


no  ANIMAL  COMMUNITIES  OF  STREAMS 

deeper  water  at  their  sources  (due  to  springs)  and  in  which  the  graded 
series  of  conditions  found  in  the  North  Shore  streams  is  wanting. 

d)  The  swift-water  fishes  begin  markedly  at  the  head  of  erosion  in 
Hickory  Creek. 

e)  The  fish  communities  differ  as  to  species  where  the  conditions 
are  very  similar,  for  example,  in  Thorn-Butterfield  and  Hickory  creeks. 
The  general  habits  of  the  fishes  are  the  same. 

/)  Larger  fishes  are  found  in  the  larger  water  course  and  in  the  down- 
stream portions  of  the  smaller  streams. 

g)  Fish,  when  entering  a  stream,  go  upstream  to  a  point  suited  to 
their  physiological  constitution,  regardless  of  its  physiographic  mode  of 
origin. 

4.   GENETIC  ECOLOGY  OF  STREAMS 

Several  years  ago  Adams  (103)  pointed  out  that  the  dispersal  of 
aquatic  animals  is  determined  by  the  shifting  backward  of  the  head- 
waters and  other  conditions  in  streams  as  erosion  proceeds.  The  forms 
that  are  in  the  young  streams  are  moved  back  as  the  headwaters  are 
moved  back  and  as  the  river  system  spreads  out  into  the  usual  fan  shape, 
the  animals  that  belonged  in  or  near  the  headwaters  move  backward  as 
the  conditions  migrate  backward.  In  a  broad  geographic  way  this  is 
unquestioned  but  details  may  be  studied  in  the  small  streams  of  the 
bluff  between  Glencoe  and  the  Wisconsin  state  line. 

Fish  are  the  only  strictly  aquatic  forms  in  these  streams  that  might 
not  have  entered  by  some  other  method  than  through  the  mouth  of  the 
stream.  We  have  made  a  study  of  the  fish  of  these  streams  for  the  pur- 
pose of  determining  whether  the  fish  in  the  headwaters  of  the  large 
streams  are  the  same  as  the  fish  that  are  found  in  streams  that  are  just 
large  enough  to  have  a  single  lish  species,  and  the  relation  of  the  animals 
to  stream  development.  The  changes  in  animal  communities  which 
take  place  at  one  point  are  called  succession. 

a)  Ecological  succession. — Ecological  succession  is  the  succession 
of  ecological  types  (physiological  t3^es,  modes  of  life)  over  a  given  point 
or  locality,  due  to  changes  of  environmental  conditions  at  that  point. 
From  this  point  of  view  we  have  nothing  to  do  with  species,  except  that  names 
are  necessary.  However,  we  may  speak  of  the  succession  in  terms  of 
species  whenever  their  life  habits  (mores)  are  not  easily  modifiable. 

Succession  always  involves  all  the  animals  of  a  community  but  it  is 
often  easier  to  discuss  the  changes  which  take  place  with  respect  to  one 
group,  such  as  the  fishes.  It  is  always  to  be  understood  that  with  changes 
in  the  fish  communities  there  are  similar  changes  in  the  communities  of 


SUCCESS  I  ox  OF  COMMUNITIES 


Other  animals  living  with  them.     To  illustrate  the  succession  of  fish  in 
streams  we  shall  consider  succession  of  fish  in  the  North  Shore  streams. 

b)  Statement  of  ecological  succession. — Succession  is  a  reconstruction. 
Here  it  is  based  on  the  superposition  of  all  the  fish  communities  (Fig.  67) 
over  the  oldest  part  of  the  oldest  and  largest  stream.  To  make  this 
clearer  we  will  state,  with  the  aid  of  the  diagram  (Fig.  69),  the  succession 
of  fish  in  Bull  Creek.     This  succession  will  be  considered  as  taking  place 


Fig.  67.— Diagrammatic  arrangement  of  the  North  Shore  streams.  The  streams 
are  mapped  to  a  scale  of  one  mile  to  the  inch,  and  the  maps  are  placed  as  closely 
together  as  possible  in  the  diagram.  The  intermediate  shore-lines  are  shown  in  broken 
lines  which  bear  no  relation  to  the  shore-lines  which  exist  in  nature.  Toward  the  top 
of  the  diagram  is  west.  Each  number  on  the  diagram  refers  to  the  pool  nearest  the 
source  of  the  stream  which  contains  fish,  as  follows:  i,  the  horned  dace  (Semotilus 
airomaculatus);  2,  the  red-bellied  dace  {Chrosomus  erythrogaster);  3,  the  black-nosed 
dace  {Rhinichlhys  atronasiis);  4,  the  suckers  and  minnows;  5,  the  pickerel  and  blunt- 
nosed  minnow;  6,  the  sunfish  and  bass;  7,  the  pike,  chub-sucker,  etc.  The  bluff 
referred  to  is  about  60  ft.  high.  The  stippled  area  is  a  plain  just  above  the  level  of  the 
lake  (see  Table  XVIII). 


over  the  oldest  part  of  the  portion  of  Bull  Creek  which  lies  back  of  the 
bluff  and  higher  levels  of  Lake  Michigan.  This  is  the  point  designated 
as  5.  (Table  XVIII  and  Figs.  67  and  69  should  be  before  the  reader.) 
When  Bull  Creek  was  at  the  stage  represented  by  the  first  stage  in 
our  diagram  (which  is  represented  by  the  present  Glencoe  Brook),  its 
fish,  if  any  were  present,  were  ecologically  similar  to  those  now  in  Glencoe 
Brook  in  their  relations  to  all  factors  except  climate.  This  ecological 
type  is  represented  by  the  horned  dace  alone.     As  Bull  Creek  eroded  its 


112 


ANIMAL  COMMUNITIES  OF  STREAMS 


bed  and  became  hypothetical  stage  C  of  the  diagram,  the  fish  community 
of  stage  I  was  succeeded  by  a  fish  community  ecologically  similar  to  the 
fish  communities  at  the  localities  marked  2  in  Fig.  67.  The  fish  now  eco- 
logically representing  this  community  are  the  horned  dace  and  the  red- 
bellied  dace.  The  community  of  the  single  species,  the  horned  dace, 
had  at  such  a  period  moved  inland  to  the  point  where  line  i-i  (Fig.  69) 
crosses  the  curved  line  representing  the  profile  of  hypothetical  stage  C. 
As  erosion  continued,  the  fish  community  ecologically  represented  by 
the  horned  dace  and  red-bellied  dace  moved  gradually  inland  and  was 
succeeded  by  a  fish  community  occupying  the  mouth  of  hypothetical 


H       G      F    E    D     C      \B 


Fig.  68. — A  diagram  showing  the  successive  stages  in  the  profile  (general  shape 
of  the  bottom)  of  a  very  young  stream,  curved  lines,  A-B,  A-C,  A-D,  A-E,  A-F, 
A-G,  A-H  representing  the  successive  profiles.  The  uppermost  horizontal  line 
represents  the  surface  of  the  land  into  which  the  stream  is  eroding.  The  horizontal 
line  with  the  arrowheads  indicates  the  migration  of  the  source  of  the  stream  and 
accordingly  of  similar  stream  conditions.  The  vertical  line  with  arrowheads  when 
followed  downward  passes  through  a  succession  of  stream  conditions  and  represents 
physiographic  succession  at  the  locality  B.  The  point  A  is  the  mouth  of  the  stream. 
Opposite  this  are  shown  three  successive  sizes  of  the  stream,  and  therefore  succession 
at  that  point. 


stage  D,  ecologically  similar  to  that  now  found  at  the  point  3.  This  is 
represented  by  the  three  daces  and  the  Johnny  darter. 

As  the  hypothetical  stage  D  eroded  its  bed  and  became  stage  E, 
which  is  represented  by  County  Line  Creek,  fish  community  3  was  then 
succeeded  by  a  fish  community  ecologically  similar  to  the  fish  community 
now  present  at  point  4.  This  is  ecologically  represented  by  the  three 
daces,  the  Johnny  darter,  and  the  young  of  the  common  sucker.  The 
fish  communities  designated  as  i,  2,  3  have  meanwhile  moved  inland  and 
are  arranged  in  the  order  which  their  ecological  constitution  requires. 

The  continuation  of  the  process  resulted  in  displacing  a  fish  com- 
munity ecologically  similar  to  the  fish  community  4  by  a  fish  community 


SUCCESSION  OF  COMMUNITIES 


113 


ecologically  similar  to  the  present  fish  community  5.     This  is  repre- 
sented in  the  lower  waters  of  Bull  Creek — stage  F, 

Ecological  succession  is  one  of  the  few  biological  fields  in  which  pre- 
diction is  possible.  We  may  carry  this  discussion  a  little  farther.  We 
have  noted  that  the  developing  streams  continue  to  erode  their  beds, 
grow  larger,  and  bring  down  the  surface  of  the  land.  These  processes 
have  not  stopped  in  Bull  Creek;  it  will  become  larger,  contain  a  larger 
volume  of  water  at  the  locality  5,  and  the  fish  community  of  locality  5 


Fig.  69. — This  figure  is  based  on  Fig.  68.  The  profiles  of  the  streams  shown 
here  are  separated  vertically  at  the  mouth.  The  curved  hnes  represent  seven  stream 
stages  as  follows:  B,  Glencoe  Brook;  C,  hypothetical  stage;  D,  hypothetical  stage; 
E,  County  Line  Creek;  F,  Pettibone  Creek;  G,  hypothetical  stage;  H,  Bull  Creek- 
Dead  River.  The  hypothetical  stages  could,  no  doubt,  be  found  along  the  shore  of 
Lake  Michigan;  the  difficulty  arises  from  the  introduction  of  sewage  into  so  many 
streams. 

The  comparative  size  of  the  mouth  of  each  stream  stage  is  represented  by  a  stream 
cross-section  at  the  right.  The  direction  of  reading  in  succession  is  indicated  by  the 
vertical  line  with  the  arrowheads  pointing  downward.  The  oblique  lines  marked 
i-i,  2-2,  ^-;^,  etc.,  pass  through  points  in  the  stream  profiles  which  are  in  the  same 
physiographic  condition  and  occupied  by  similar  fish  communities. 


will  be  succeeded  by  a  fish  community  ecologically  similar  to  that  now 
at  locality  6.  This  stage  has  been  designated  as  hypothetical  stage  G 
in  the  diagram.  With  a  further  continuation  of  the  process,  the  fish 
community  of  stage  G,  locality  6,  will  be  succeeded  by  a  fish  community 
ecologically  similar  to  that  now  found  at  the  locality  7  (Dead  River) — ■ 
stage  H.  The  communities  of  every  stream  have  some  such  history  as 
we  have  reconstructed,  but  the  details  may  be  modified  by  conditions. 
That  branch  of  ecology  which  deals  with  such  histories  is  called  genetic 
ecology. 


114 


ANIMAL  COMMUNITIES  OF  STREAMS 


TABLE  XVII 

Distribution  of  Invertebrates  in  North  Shore  Streams 
The  meaning  of  the  numbers  is  shown  in  Figs.  67  and  69.     0  =  Temporary  pool 
(consocies);  6  =  Very  young  stream  and  intermittent  riffles  (ephemeral  consocies). 


Common  Name 

Caddis-worm 

Mosquito  larva 

Amphipod 

Isopod 

Snail 

Crayfish 

Black-fly  larva 

May-fly  njTnph 

Crayfish 

Burrowing  dragon-fly 

Dragon-fly  nymph. .  . 

Amphipod 

Snail 

Crayfish 

Crayfish 

Crane-fly  larva 

Amphipod 

Snail 

Dragon-fly  nymph. .  . 


Scientific  Name 

Phryganeidae 

Anopheles 

Eucrangonyx  gracilis 

Smith 

Asellus  communis  Say..  . 
Lymnaea  tnodicella  Say. . 
Cambarus  dio genes  Gir  .  . 

Simulium  sp 

Heptageninae 

Cambarus  blandingi 

acutus  Girard 

Cordulegaster  obliquus 

Say 

Aeschna  constricta  Say..  . 
Gammarus  fasciatus  Say . 

Physa  gyrina  Say 

Cambarus  virilis  Hag  .  .  . 
Cambarus  propinquus  Gir 
Pedicia  albivitta  Walk 

(rarely) 

Hyalella  knickerbockeri 

Bate 

Planorbis  campanidatus 

Say 

Tetragoneuria  cynosura 

Say 


STREAM  ANIMALS 


115 


*  TABLE  XVIII 

Showixg  the  Distribution  of  Fish  (Nomenclature  after  79)  in  the  North 

Shore  Streams  at  the  Times  Indicated 

(The  numbers  refer  to  Figs.  67  and  69) 


Name  of  Stream  and  Common 
Name  of  Fish 

Date  and  Scientific  Name 

I 

2 

3 

4 

s      6:7 

Glencoe  Brook 

Homed  dace 

August,  1907 

Semotilus  atromaculalus. .  . 

1907-8 

Semotilus  atromaculatus. .  . 

Rhinichthys  atronasus .... 

Bolcosoma  nigrum 

Pimephales  promelas 

Pimephales  notatus 

Catoslomus  commersonii  .  . 
September,  1909,  and  April, 
1910 

Semotilus  atromaculatus  .  . 

Chrosomus  erythrogaster. .  . 

Rhinichthys  atronasus .... 

Bolcosoma  nigrum. 

Catoslomus  commersonii. .  . 
September,  1909 

Semotilus  atromaculatus. .  . 

Chrosomus  erythrogaster..  . 

Rhinichthys  atronasus .... 

Catoslomus  commersonii. .  . 

Pimephales  notatus 

Esox  vermiculatus 

Lepomis  pallidus 

Micro  pterus  salmoides.  . .  . 

Esox  lucius 

Pomoxis  annularis 

Moxostoma  aureolum 

Erimyzon  sucetta 

Abramis  crysoleucas 

Notropis  cornutus 

Notropis  cayuga 

* 
* 

? 
* 

* 

* 
* 

* 
* 

* 
* 
* 

* 
* 
* 
* 

* 
* 

* 
* 

* 

* 
* 

* 
* 

* 

* 

* 

* 
* 
* 
* 

County  Line  Creek 

Horned  dace 

Black-nosed  dace 

Johnny  darter 

Blackhead  minnow 

Blunt-nosed  minnow .... 

Common  sucker 

Pettibone  Creekf 

Horned  dace 

Red-bellied  dace 

Black-nosed  dace 

Johnny  darter 

Common  sucker 

Bull  Creek-Dead  River 

Horned  dace 

1 
] 

*  1 

Red-beUied  dace 

Black-nosed  dace 

Common  sucker 

Blunt-nosed  minnow  .... 
Little  pickerel 

* 
* 
* 

* 
*     * 

Bluegill       .... 

*  1  * 

Large-mouthed  black  bass 

Pike 

Crappie 

Red-horse 

* 

* 
* 
* 
* 

Chub-sucker 

* 

Golden  shiner 

* 

Common  shiner 

Cayuga  minnow 

Tadpole  cat 

* 

Schilbeodes  gyrinus 

* 

t  The  lower  part  of  Pettibone  Creek  has  been  destroyed  by  the  United  States  Naval  School,  other- 
wise the  table  would  include  the  records  for  a  point  5  and  perhaps  a  point  6,  but  probably  not  7 


Note.— Table  XDC  follows  Table  XX. 


ii6 


ANIMAL  COMMUNITIES  OF  STREAMS 


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STREAM  ANIMALS 


117 


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ii8 


ANIMAL  COMMUNITIES  OF  STREAMS 


TABLE  XIX 

Animals  of  Springs  and  Spring  Brooks 
The  meaning  of  the  letters  in  the  column  headed  "Location"  is  as  follows: 
Cs  =  Gary  spring;   Gs  =  Gaugars  spring;   Zs  =  Zion  spring;   Sb  =  Suman  spring  brook; 
Cb  =  Gary  spring  brook. 


Common  Name 

Amphipod 

Planarian 

Planarian 

Dragon-fly  nymph. 

Midge  larva 

Black-fly  lar\'a .... 

Gaddis-worm 

Midge  larva 

Fly  larva 

May-fly  nymph .  .  . 

Bivalve 

Amphipod 

Crayfish 

Snail 

Damsel-fly  nymph. 
Parnid 


Scientific  Name 

Gammarus  fasciatus  Say .  .  . 

Planar ia  dorotocephala 

Dendrocoelum  sp 

Aeschna  sp 

T any pus  sp 

Simulium  sp 

Hydro  psyche  sp 

Chironomus  sp 

Dixa  sp 

Heptagenia 

Musculium 

Eucratigonyx  gracilis  Smith 
Cambarus  propinqims  Gir.  . 

Physa  gyrina  Say 

Calopleryx  maculata  Beauv . 
Elmis  fastiditus  Lee 


Location 


Gs, 
Gs 
Gs 
Gs 


Gs,  Zs 


Zs 


Sb 

Sb,  Cb 
Cb 
Cb 
Cb 
Cb 
Cb 
Cb 
Cb 
Cb 
Cb 
Cb 


STREAM  ANIMALS 


119 


♦  TABLE  XXI 

The  Distribution  of  Fish  (Nomenclature  after  79)  in  Hickory  Creek  (and 
Its  West  Branch)  in  the  Summer  of  1909 
Those  starred  were  in  the  pool  nearest  the  source.  I,  the  first  mile  of  the  stream, 
measured  from  the  fish  pool  nearest  the  source,  toward  the  mouth;  II,  the  third  and 
fourth  miles;  III,  at  the  head  of  erosion,  five  miles  from  the  pool  nearest  the  source; 
IV,  six  miles  from  the  pool  nearest  the  source;  V,  nine  miles  from  same;  stream  much 
larger  with  good  riffles  and  one  weedy  cove. 


Common  Name 


Scientific  Name 


Horned  dace* 

Golden  shiner* 

Johnny  darter* 

Stone-roller* 

Straw-colored  minnow*. . . 
Blue-spotted  sunfish* .... 

Blunt-nosed  minnow 

Common  sucker* 

Mud  minnow 

Top  minnow 

Red-beUied  dace 

Chub-sucker 

Black  bullhead 

Blackfin 

River  chub 

Fan-tailed  darter 

Rainbow  darter 

Least  darter 

Sucker-mouthed  minnow . 

Cayuga  minnow 

Rock  bass 

Common  shiner 

Rosy-faced  minnow 

Banded  darter 

Bluegill 

Long-eared  sunfish 

Stonecat  

Yellow  perch 

Small-mouthed  black  bass 

Hogsucker 

Common  red-horse 


Semolilus  atromaculatus 
Abramis  crysoleucas . .  .  . 

Boleosoma  nigrum 

Campostoma  anomalum. 

Notropis  blenniiis 

Lepomis  cyanellus 

Pimephales  notatus 

Catostomus  commersonii. 

Umbra  limi 

Fundulus  notatus 

Chrosomus  erythrogaster. 

Erimyzon  sucetta 

Ameiiirtts  melas 

Notropis  nmbratilis .... 
Hybopsis  Kentuckiensis 
Etheostoma  flabellare . .  . 
Etheostoma  coeruleum .  . 
Microperca  punctulata. . 
Phenacobius  mirabilis .  . 

Notropis  cayuga 

Amblopliies  riipestris.  . . 

Notropis  cornutus 

Notropis  riibrifrons .... 

Etheostoma  zonale 

Lepomis  pallidus 

Lepomis  megalotis 

Notiirus  flavus 

Perca  flavescens 

Micropterus  dolomieii .  . . 
Catostomus  nigricans .  . . 
Moxostoma  aureolum . . . 


Ill 


IV 


I20 


ANIMAL  COMMUNITIES  OF  STREAMS 


TABLE  XXII 

The  Fish  (Nomenclature  after  79)  of  Thorn  Creek,  Collection  Made  at  the 
Headwaters  in  1908  and  1909  and  at  Other  Points  in 
1909  AND  1910 
A  =  the  first  fish  pool;    B  =  four  miles  downstream;    C  =  ten  miles  downstream. 


Common  Name 

Horned  dace 

Blunt-nosed  minnow 

Blue-spotted  sunfish  .... 
Stone- roller 

Banded  darter 

Common  shiner 

Striped- top  minnow 

Black-sided  darter 

Johnny  darter 

Mud  minnow 

Cayuga  minnow 

Golden  shiner 

Large-mouthed  black  bass 
Small-mouthed  black  bass 

Bluegill 

Crappie 

Pirate  perch 

Yellow  perch 

Carp 

Black  bullhead 

Common  sucker 

Short-headed  red-horse. . . 
Pike 


Scientific  Name 

Semotilus  atromaculatus 
Pimephales  notatus .... 

Lepomis  cyanellus 

Camposlotna  anomalum. 
Notropis  umbratilis .  .  .  . 

Etheosloma  zonale 

Notropis  cormitus 

Fundulus  dispar 

Hadroplerus  aspro 

Boleosoma  nigrum 

Umbra  limi 

Notropis  cayuga 

Abramis  crysoleucas .  .  . 
Micropterus  salmoides .  . 
Micropterus  dolomieu.  . 

Lepomis  pallidus 

Pomoxis  sparoides 

Aphredoderus  sayanus . . 

Perca  flavescens 

Cyprinus  carpio 

Ameiurus  melas 

Catostomus  commersonii 
Moxostoma  breviceps .  .  . 
Esox  liiciiis 


STREAM  ANIMALS 


121 


«  TABLE  XXIII 

Animals  of  the  DesPlaines,  Chicago,  and  DuPage  Rivers 
The  meaning  of  the  letters  in  the  column  headed  "Location"  is  as  follows: 
L  =  Libert}^4lle  (still-silt);  W  =  Wheeling  (mud-gravel) ;  D  =  DuPage;  R  =  Riverside 
(swift-stones).  Liberty\'ille  is  the  farthest  upstream,  and  the  other  situations  follow 
in  the  order  named.  C  =  Chicago  River  at  Edgebrook,  which  is  added  without 
regard  to  longitudinal  order. 


Common  Name 


Crayfish 

Snail 

Dragon-fly  nymph .  . 

Snail 

Snail 

Crayfish 

Craj^sh 

Mussel 

Mussel 

Mussel 

Mussel 

Bivalve 

Snail 

Mussel 

Snail 

Snail 

Snail 

Mussel 

Snail 

Snail 

Stone-flies 

Dobson 

Amphipod 

Caddis- worm 

Isopod 

Damsel-fly  nymph .  . 

Dytiscid 

Newt 

Polyzoan 

Pamid 

Caddis- worm 

Leech 

Caddis- worm , 

Sialid 

Sphaerid 

Burrowing  dragon-fly 
nymph 


Scientific  Name 


Cambarus  virilis  Hag 

Lymnaea  humilis  nwdicella  Say 

Basiaeschna  janata  Say 

Ancylus  tardus  Say 

Ancylus  rivularis  Say 

Cambarus  propinquus  Gir 

Cambarus  diogenes  Gir 

Anodonta  grandis  Say 

Anodontoidcs  ferussacianus  Lea 

Quadrula  uudiilata  Bar 

Lampsilis  luteola  Lam 

Musculium  truncalum  Lins. .  . 

Goniohasis  livescens  Mke 

Alasmidonla  calceola  Lea.  .  .  . 

Amnicola  limosa  Say 

Planorbis  bicarinatus  Say.  .  .  . 

Physa  gyrhia  Say 

Lampsilis  ellipsiformis  Con .  . 
Pleurocera  subulare  intensum 

Ant 

Pleurocera  elevatum  Say 

Perla  sp 

Corydalis  cornuia  Linn 

Hyalella  knickerbockeri  Bate. . 

Hydropsyche 

Asellus  communis  Say 

Argia  sp 

Hydro porus  viUatus  Lee 

Diemictylus  viridescens  Raf . .  . 

Plumaiella  sp 

Elmis 

Helico psyche  sp 

Haemopis  grandis  Verrill .... 

Phryganeidae 

Sialis  sp 

Sphaerium  stamineum  Con. . . 

Gomphus  exilis  Selys 


Location 


R 

R 
R 

R 

R 

R 


D 

D 

D 
D 
D 
D 
D 
D 
D 

D 

D 


D 


C 
W 
C 
W 
C 
W 
W 
W 
W 


122  ANIMAL  COMMUNITIES  OF  STREAMS 

TABLE  XXIV 

Mussels  of  the  Calumet-Deep  River.    Arranged  in  Order  of  Longitudinal 
Succession  Beginning  with  the  Upper  Parts  of  the 
River  at  Ainsworth 
The    letters    indicate    place    of    collection.      A  =  Ainsworth;     G  =  East    Gary; 
M  =  south  of  Miller,  in  the  Little  Calumet;  and  C  =  Clark,  in  the  Grand  Calumet. 


Common  Name 

Scientific  Name 

Location 

Mussel    

Symphynota  costata  Raf 

A 

G 
G 
G 

M 
M 
M 
M 
M 
M 

Mussel 

Mussel 

LampsiUs  ventricosa  Bar A 

Quadrula  undulala  Bar A 

LampsiUs  luteola  Lam 1      A 

Symphynota  complanata  Bar. .  .       A 

Undo  gibbosus  Bar 

Quadrula  rubiginosa  Lea i 

Anodonta  grandis  Say 

Mussel 

Mussel  

Mussel     

Mussel 

Mussel 

C 

STREAM  ANIMALS 


123 


*  TABLE  XXV 

Animals  from  a  Sluggish  Portion  of  Fox  River 
The  meaning  of  the  letters  in  the  column  headed  "Location"  is  as  follows: 
Gm=gravel  in  mid  river  in  eight  feet  of  water;    G=gravel  near  shore;    S  =  sand; 
M  =  mud  or  silt;  V= vegetation. 


Common  Name 


Scientific  Name 


Location 


Snail 

Mussel 

Mussel 

Mussel 

Red  midge  larva .  . 
Green  midge  lar\'a . 

Caddis- worm 

Polyzoan 

Dragon-fly  nymph . 

Crayfish 

Snail 

Snail 

Mussel 

Mussel 

Mussel 

May-fly  nymph .  .  . 

Fly  larva 

May-fly  nymph .  .  . 

Amphipod 

Ma3'-fly  nymph .  .  . 

Beetle 

Sialid  larva 

Snail 

Water-boatman.  .  . 
Water  scorpion. .  . . 

Amphipod 

Bug 

Parnid 

Creeping  bug 


Back-swimmer.  . . . 
Dragon-fly  nymph. 

Leech 

Top  minnow 


Snail. 


Gomohasis  livescens  Mke. . 
Anodonta  grandis  Say.  . . . 
Lampsilis  ligamenlina  Lam 
Quadrula  undulata  Bar.  .  . 

Chirouomus 

C/iironomus 

Hydro  psyche 

Phimatella 

Macromia  iaeniolaia  Ram. 
Cambanis  propinquus  Gir. 
Campeloma  inlegrum  DeK. 
Phurocera  elevatum  Say. . . 

Unio  gibbosus  Bar 

Quadrula  rubiginosa  Lea .  . 
Lampsilis  luteola  Lam..  .  . 

Hexagenia 

Stratiomyia  sp 

Callibaetis  sp 

Hyalella  knickerbockeri  Ba. 

Cacnis  sp 

Donacia 

Chauliodes  sp 

Physa  integra  Hald 

Corixa  sp 

Ranatra  fusca  Beau 

Gammarus fascialus  Say.  . 

Zaitha  fluminea  Say 

Elmis  4-notatus  Say 

Pelocoris  femoraliis  Pal 

Beauv 

Notonecta  variabilis  Fieb .  . 
Ischnura  verlicalii  Say. .  .  . 
Glossiphonia  fusca  Castle . 
Fuiidulus  diaphanus 

menona  J.  and  C 

Planorbis  bicarinatus  Say . 


Gm 
Gm 
Gm 
Gm 
Gm 
Gm 
Gm 
Gm 


M 


M 
M 
M 


V 
V 
V 
V 
V 
V 
V 
V 
V 
V 
V 
V 

V 
V 

V 
V 

V 
V 


CHAPTER  VII 

ANIMAL  COMMUNITIES  OF  SMALL  LAKES 

I.    Introduction 

Lakes  are  difficult  to  classify  on  the  basis  of  animal  relations.  This 
is  because  size,  shape,  exposure  to  wind,  depth,  and  age  are  all  important 
in  determining  conditions  that  aflfect  animals.  A  classification  into 
coastal  lakes  and  morainic  lakes  will  serve  our  purposes  best,  because, 
other  things  being  equal,  it  represents  age  and  depth  (near  Chicago). 

Morainic  lakes  are  depressions  in  the  moraine  due  to  irregularities  of 
deposition,  which  stand  below  ground-water  level.  They  are  of  various 
sizes.  We  shall  apply  the  term  lake  only  to  those  bodies  of  water  that 
are  large  enough  to  produce  an  area  of  at  least  a  few  square  rods  of 
sandy  shore,  which  supports  gilled  snails,  mussels,  etc.  The  principal 
lakes  included  in  our  area  are  shown  on  the  map  facing  p.  52.  The 
largest  of  these  are  the  Fox,  Pistakee,  Maria,  and  Grass  lakes  in  northern 
Illinois;  Hudson,  Cedar,  Stone,  and  Flint  lakes  in  Indiana;  and  Paw 
Paw  and  Pipestone  lakes  in  Michigan.  The  only  coastal  lakes  of  any 
size  are  Wolf  Lake  and  Calumet  Lake.  These  are  located  in  the  old  Lake 
Chicago  plain. 

I.      CONDITIONS   IN   LAKES 

Depth  is  important  in  determining  the  conditions  at  the  bottom,  but 
is  of  little  importance  to  the  other  parts  of  the  lake.  Little  is  known  of 
the  depths  of  our  lakes.  Exposure  to  wind  is  of  importance  in  affecting 
the  waves  and  circulation  of  the  water  (see  p.  61),  both  of  which  are 
important  to  animals.  A  lake  well  protected  by  high  hills  will  be  likely 
to  be  less  affected  by  wind  than  others.  Shape  is  also  a  factor.  Long 
lakes  whose  long  axes  are  parallel  with  the  direction  of  the  prevailing 
winds  are  more  strikingly  affected  by  the  wind  than  those  with  the  long 
axis  at  right  angles  to  the  wind. 

Waves  are  never  large  on  small  lakes,  but  are  usually  effective  in 
determining  the  kind  of  bottom  by  controlling  erosion  and  deposition. 
The  general  circulation  of  all  our  lakes  has  not  been  studied.  On 
account  of  their  small  size  it  is  probable  that  the  deeper  ones  at  least 
have  an  incomplete  circulation  like  that  indicated  in  P'ig.  11,  p.  61. 
Those  that  get  warmed  throughout  in  summer  probably  have  a  complete 
circulation.     The  dissolved  content  of  the  waters  of  lakes  is  usually 

124 


LIMNETIC  COMMUNITY 


125 


similar  to  that  of  the  large  lakes  and  rivers.  Oxygen  is  usually  abundant 
in  the  surface  waters,  but  is  often  wanting  in  the  bottoms  of  lakes  (74) 
with  incomplete  summer  circulation.  Muck  bottoms  in  deep  water 
or  in  bays  have  little  or  no  dissolved  oxygen.  Dissolved  nitrogen  is 
important,  but  has  been  little  studied.  In  the  open  water  light  and 
pressure  are  governed  by  the  same  factors  as  in  the  large  lakes  (see 
pp.  62-64).  The  bottom  in  small  lakes  varies  with  exposure  to  waves. 
Where  the  waves  are  eroding,  the  bottom  is  stony  or  sandy;  where  deposit- 
ing, it  contains  silt  and  humus.  There  are  often  deposits  of  marl,  which  is 
a  calcium  carbonate  deposit,  frequently  reaching  a  depth  of  18  feet  in  the 
Indiana  lakes.  It  frequently  reaches  to  the  surface  of  the  water,  but 
when  it  does  so  is  often  covered  by  muck.  Muck  bottom  is  common  in 
the  deeper  water  and  in  bays.  The  vegetation  in  such  lakes  is  very  much 
like  that  in  base-level  streams.  The  vegetation  of  the  shores  of  rivers 
like  Fox  River  is  duplicated  in  these  lakes,  and  in  fact,  small  lakes  are 
strictly  comparable  to  sluggish  rivers  in  many  respects.  We  have 
patches  of  vegetation,  patches  of  sand  and  gravel  bottom,  but  also  much 
bottom  which  has  more  organic  matter  than  river  silt.  The  principal 
difference  is  that  currents  in  the  lakes  vary  with  the  wind,  and  in  sluggish 
streams  are  mainly  in  one  direction. 

II.     Communities  of  Small  Lakes 

(Stations  30,  30a,  31;  Table  XXVI) 

These  are  divided  into  the  limnetic  formation,  the  formations  of 

sandy  and  stony  shores,  the  formations  of  muck  bottom  in  shallow 

water,  the  formations  of  the  vegetation,  and  the  formations  of  deep 

water  (anaerobic). 

I.      THE   LIMNETIC   FORMATION    (104) 

(List  II) 
The  limnetic  formation  of  the  smaller  lakes  is  very  similar  to  that  of 
the  larger  lakes.  It  is  made  up  of  the  same  groups,  but  with  the  addition 
of  a  few  pelagic  insects  such  as  the  phantom  larva  {Corethra  sp.).  The 
species  of  crustaceans,  rotifers,  and  protozoa  are  different.  The  char- 
acters of  the  formation  are  similar  to  those  of  Lake  Michigan  (p.  75). 

2.      SHALLOW   WATER   FORMATIONS 

a)  Terrigenous  bottom  formation  (105). — Vegetation  sparse  or  absent 
— water  0-3  meters.  Crawling  over  the  sandy  bottom  are  usually  found 
caddis- worms  {Goera  sp.  or  Molanna  sp.)  (Figs.  70,  71).     These  forms 


126 


COMMUNITIES  OF  SMALL  LAKES 


belong  to  different  families,  but  have  similar  cases  and  similar  habits. 
This  is  a  good  example  of  what  is  meant  by  mores.  The  forms  are  very 
different,  but  their  mores  are  similar.  The  Johnny  darter,  the  straw- 
colored  minnow  (Fig.  72),  and  the  blunt-nosed  minnow  are  usually 
found  (105)  in  the  shallowest  water.  The  Johnny  darter,  the  blunt- 
nosed  minnow,  the  miller's  thumb,  and  probably  other  minnows  breed 
in  these  situations  (105,  106).  Crayfish  are  common  here  (in  Wolf  Lake, 
Cambarus  virilis). 

Snails  (such  as  Pleurocera  subulare  [Fig.  73],  and  sometimes  Goniobasis 
livescens)  are  common  on  the  shoals,  crawling  over  the  bottom  which  is 
always  covered  with  diatoms,  desmids,  etc.     These  algae  serve  as  food 

for  the  mussels.  Miss  Nichols 
found  16  species  of  algae  on  the 
shell  of  a  specimen  of  Pleurocera 
taken  from  a  Wolf  Lake  shoal. 
In  the  deeper  waters  (3  ft.)  we 
find  the  same  crayfishes  and  the 
same  snails  fewer  in  number 
than  in  the  shallower  parts  of 
the  shoals.  Associated  with 
them  are  the  mussels  (especially 
Lampsilis  luteola,  Anodonta  mar- 
ginata  and  grandis) .  Such  sandy 
and  gravelly  bottomed  shoals  in 
1-3  ft.  of  water  are  especially 
important  to  the  food  fishes. 
There  are  many  first-class  food 
fishes  in  all  such  lakes.  Of 
those  in  Wolf  Lake  seven  breed 
in  these  shallows.  There  are  the  large-mouthed  black  bass  (Fig.  74), 
the  bluegill,  the  pumpkinseed,  the  green  sunfish,  the  perch  (Fig.  75),  the 
speckled  catfish,  and  the  crappie.  Nearly  all  in  making  their  nests 
scrape  the  bottom  clear  of  all  debris;  the  males  guard  the  nests.  The 
number  of  food  fishes  in  a  lake  is  related  to  the  area  of  such  shoals,  which 
are  accordingly  of  great  economic  importance  and  should  be  protected 
from  destruction  by  the  encroachment  of  vegetation  and  accumulation 
of  debris.  Associated  with  the  fish  are  occasional  musk  turtles  {Aro- 
mochelys  odorata).  Shoals  are  invaded  by  bulrushes  and  bare  bottom 
may  exist  between  them.  Here  the  viviparous  snail  {Vivipara  contec- 
toides)  (Fig.  76)  sometimes  occurs. 


Fig.  70. — The  case  of  a  caddis-worm  {Mol- 
anna  sp.),  sandy  bottom  (Fox  Lake,  111.) 
(original) . 

Fig.  71. — The  same  from  below. 


BOTTOM  COMMUNITIES 


v»tvvV^V#V**> 


<>m^fi. 


~-h^ 


72 


73, 


Representatives  of  the  Bare  Saxd  Community 

Fig.  72. — Straw-colored  minnow   {Notropis  hktutiiis)   (from  Forbes  and  Rich- 
ardson) . 

Fig.    73. — Snail   (Pleurocera  siibiilare)    crawling   o\er   sand}'   bottom;    slightly 
enlarged  (photographed  in  aquarium). 

Fig.  74. — ^Large-mouthed  black  bass  {Micro pterus  salmoides),  juvenile;  natural 
size  (original). 


I2i 


COMMUNITIES  OF  SMALL  LAKES 


Characters  of  the  formation :  The  formation  is  distinctly  dependent 
upon  a  clean  bottom  of  sand  or  coarser  materials,  and  is  made  up  of 
creeping  forms  and  those  using  the  bottom  as  a  breeding-place. 


Representative  Animals  of  the  Submerged  Vegetation 

Fig.  75. — Upper  fish,  the  green  sunfish  {Lepomis  cyanellus);  lower  fish,  the  yellow 
perch  {Perca  flavescens);  both  juvenile;  slightly  reduced  (original). 

Fig.  76. — A  viviparous  snail  (Vivipara  contecloides);  natural  size. 

Fig.  77. — A  winter  body  or  statoblast,  of  the  gelatin-secreting  polyzoan  {Pectina- 
tella  magnifica);   10  times  natural  size  (original). 

Fig.  78. — ^A  shrimp  {Palaemonetes  paludosus);  twice  natural  size  (original). 

h)  Submerged  vegetation  association  of  the  open  waters. — A  lake  of  the 
coastal  type  is  separated  rapidly  from  the  larger  body  of  water  in  con- 
nection with  which  it  is  formed,  or  a  morainic  lake,  when  the  ice  retreats, 


VEGETATION  COMMUNITIES  129 

is  left  with  the  greater  part  of  its  shallow  water  of  the  type  which  we  have 
described.  Vegetation  is  present  from  the  first  in  the  form  of  floating 
microscopic  plants,  and  the  dead  bodies  of  these  and  of  the  animals 
present  are  swept  into  the  depressions  and  protected  situations  where  the 
waves  do  not  drag  on  the  bottom.  Here  vegetation  grows  in  the  greatest 
luxuriance  and  causes  the  production  of  more  plant  debris,  which  adds 
to  that  already  in  the  protected  situations.  We  then  have,  after  a  time, 
a  covering  of  the  bottom  by  the  humus  and  conditions  unfavorable  for 
most  bottom  animals.  The  animals  of  the  bare  bottom  shoals  are  no 
longer  present  in  numbers.  Small,  apparently  stunted  forms  of  Lampsilis 
luteola  are  found  for  a  time,  but  are  soon  driven  out  by  the  increase  of 
humus  and  vegetation.  The  early  vegetation  is  made  up  of  scattered 
aquatic  plants,  such  as  Myriophylluni  and  Elodea,  and  in  the  shallower 
water  usually  bulrushes. 

One  of  the  most  distinctive  and  characteristic  forms  of  such  lakes  is  a 
transparent  true  shrimp  {Palaemonetes  paludosus),  about  2  inches  long 
(Fig.  78),  which  is  a  close  relative  of  some  of  the  edible  marine  shrimps. 
In  spring  they  are  found  carrying  numbers  of  green  eggs  attached  to  the 
appendages  of  their  abdomens.  Another  common  animal  in  these 
situations  is  the  large  polyzoan  {Pectinatella  magnifica).  This  is  a 
colonial  form  which  reproduces  by  budding  in  several  directions.  It  also 
secretes  a  clear  and  transparent  jelly.  As  the  number  of  animals 
increases  the  amount  of  jelly  increases  on  all  sides  and  the  animals  are 
arranged  on  the  outside  of  the  more  or  less  spherical  mass  of  jelly;  the 
necessary  increase  in  surface  for  the  growth  of  the  colony  is  supplied 
through  additional  secretion  by  each  new  animal  added.  Some  of  these 
masses  of  jelly  reach  a  size  of  6  inches  in  diameter.  They  are  often 
attached  about  a  stalk  of  Myriophylluni  as  a  center.  In  the  autumn 
they  form  bodies  known  as  statoblasts  (Fig.  77),  which  are  disk-shaped, 
the  center  containing  living  cells  and  the  rim  being  filled  with  air-bubbles. 
The  rim  of  the  disk  is  supplied  with  hooks  which  catch  onto  objects. 
Probably  they  must  be  frozen  before  they  will  grow  into  new  colonies 
for  they  do  so  only  in  the  spring. 

Other  characteristic  animals  of  this  open-water  vegetation  are 
shelled  protozoa  (Fig.  79),  water-mites  (Fig.  80),  and  ostracods  (Fig.  Si). 
On  the  stems  of  the  water  plants,  such  as  bulrushes  and  pickerel  weed, 
are  the  snails  (Ancylus)  which  belong  to  the  lunged  group,  but  are  said 
to  take  water  into  the  lung  and  thus  do  not  need  to  come  to  the  surface 
for  air.  Occasional  snails,  leeches,  and  midge  larvae  occur.  Water- 
mites  fasten  their  eggs  to  the  bases  of  the  aquatic  plants.     Among  the 


I30 


COMMUNITIES  OF  SMALL  LAKES 


leaves  of  the  divided  leaved  plants  the  midge  larvae,  damsel-fly  nymphs, 
and  May-fly  nymphs  (Callibaetis  sp.)  are  usually  numerous.  All  these 
are  important  as  fish  food.  This  area  is  the  feeding-place  for  a  number 
of  fishes.  Those  feeding  in  the  vegetation  are  the  sul^fishes,  basses  and 
perches,  most  of  which  breed  on  the  barren  shoals.  With  them  are  also 
the  carp,  the  chub-sucker,  the  warmouth  bass,  the  brook  silverside 
(Labidesihes  sicculus),  and  the  buffalo  fish  (84).  This  part  of  the  lake  is 
also  the  favorite  haunt  of  the  turtles  (107),  such  as  the  soft  shell  {Aspi- 
donectes  spinifer),  and  in  the  parts  with  some  bare  bottom,  the  musk 


80  ^  81(^ 

Fig.  79. — Shelled  protozoan  {Diffliigia  pyriformis  Perty.)  (after  Leidy) . 
Fig.  80. — A  red  mite  {Limnochares  aqiiaticus) ;  6  times  natural  size  (after  Wolcott). 
Fig.  8i. — Dorsal  view  of  an  ostracod  {Cypridopsis  vidua);   80  times  natural  size 
(after  Brady). 

Fig.  8ia. — The  same  seen  from  the  side. 


turtle  (Aromochelys  odorata),  and  the  geographic  turtle  {Graptemys  geo- 
graphicus).  The  mud  puppy  (Nedurus  macidosus)  is  also  found  in  such 
situations  {fide  Mr.  Hildebrand).  The  muskrat  {Fiber  zibethicus) 
builds  its  nest  (Fig.  82)  in  the  shallow  water  adjoining  these  situations. 
The  musk  turtle  frequently  deposits  its  eggs  on  the  nest  in  early 
summer  (105).  We  have  found  them  in  these  situations  in  the  month 
of  June.  Various  aquatic  birds  feed  here  (108).  This  formation  may 
be  characterized  as  belonging  to  the  aquatic  vegetation,  but  practically 


V  EG  ETA  TIOX  COMMUNITIES 


131 


all  the  species  are  relatively  independent  of  the  atmosphere  and  of  the 
bottom. 

c)  Emerging  vegetation  association  of  bays. — Such  situations  as  are 
occupied  by  this  association  are  found  in  bays  and  protected  situations  in 
the  larger  lakes  and  represent  a  stage  which  is  last  in  the  history  of  a 
lake.  Water-lilies,  water  buttercups,  and  Myriophylluni  are  the  prin- 
cipal plants.  Filamentous  algae  are  usually  very  ainnidant.  Logs, 
sticks,  and  pieces  of  wood  are  not  uncommon. 

On  the  under  side  of  logs,  we  find  such  forms  as  the  polyzoan 
(Plumatella)  and  sponges  (Spongilla  sp.).  On  the  under  side  of  the  water- 
lily  pads  are  usually  numbers  of  Hydra  together  with  great  numbers  of 


Fig.  82. — A  muskrat's  nest  adjoining  the  lake  border  among  the  biilrushes  on 
sandy  bottom. 

shelled  protozoans  and  rotifers,  especially  sessile  forms.  Snails  also  are 
common  here  {Segmentina  armigera,  Planorbis  parvus,  Physa  gyrina  and 
Integra,  Planorbis  campanulatus,  and  some  species  of  Lymnaea). 

A  large  number  of  species  of  aquatic  insects  cling  in  the  vegetation 
vdth.  the  abdomen  near  the  surface  of  the  w^ater  and  secure  air  through 
various  anatomical  arrangements  which  conduct  it  to  the  spiracles;  the 
most  noteworthy  of  these  are  the  water  scorpion  (Ranatra),  the  electric- 
light  bugs  (Benacus  and  Belostoma),  the  predaceous  diving  beetles 
iPytiscidae)  (99c),  the  water  scavengers  (Hydrophilidae),  and  the  water- 
boatmen  (Corixa).  There  are  also  a  number  of  aquatic  insects  that  are 
not  dependent  upon  the  atmospheric  air  in  their  young  stages.  They 
require,  however,  some  object  which  reaches  above  the  surface  of  the 


132  COMMUNITIES  OF  SMALL  LAKES 

water  when  they  emerge  from  the  larval  skin.  The  prominent  members 
of  this  group  are  the  dragon-fly  nymphs  {Anax  Junius  and  Ischnura 
verticalis) . 

There  are  a  few  insects  that  are  relatively  independent  of  vegetation 
as  a  means  of  attachment.  The  back-swimmers  are  an  example.  They 
float  or  swim  in  the  water  among  the  vegetation.  The  commonest  of 
these  are  those  belonging  to  the  genera  Plea,  Notonecta,  and  Buenoa. 
There  are  a  few  fish  that  have  a  similar  habit.  The  top  minnow 
(Fundulus  dispar),  which  feeds  at  the  surface,  is  an  example.  It  invades 
the  pools  near  shore  and  devours  mosquito  larvae.  The  young  of  such 
fishes  as  the  basses  and  the  sunfishes  are  sometimes  taken  in  these 
situations. 

In  the  mud  of  the  bottom  there  are  but  few  animals.  Some  of  these 
are  the  same  species  as  those  found  in  the  bottom  in  the  region  of  open 
water  and  will  be  discussed  later.  There  are,  however,  forms  that  live 
only  on  the  rhizomes  of  the  water-lily.  Certain  of  the  leaf-feeding 
beetles  {Chrysomelidae,  Donacia)  (109)  are  aquatic  in  the  young  stages. 
The  female  eats  a  hole  in  the  leaves  of  the  water-lilies  and  reaches 
through  with  her  ovipositor  and  deposits  the  eggs  in  a  semicircle  which 
has  the  hole  as  its  center.  When  these  eggs  hatch  the  larvae  crawl  to  the 
rhizomes.  They  are  not  provided  with  gills  and  do  not  come  to  the 
surface  for  air.  They  have  a  pair  of  spines  adjoining  the  spiracles. 
These  spines  are  thrust  into  the  plant  and  the  spiracles  which  open  at 
their  bases  come  into  contact  with  the  holes;  the  gas  in  the  plant  and 
the  gas  in  the  air  tube  of  the  insect's  body  interchange,  and  the  animal  is 
thus  supplied  with  oxygen.  When  the  larva  is  ready-  to  pupate  it  spins 
a  cocoon  in  some  unknown  way  under  water,  but  when  it  is  completed 
it  is  filled  with  gas,  not  water,  and  surrounds  the  body  of  the  animal. 
The  animal  then  eats  a  hole,  connecting  the  cocoon  with  the  air  spaces 
of  the  plant.  It  then  pupates  and  is  supplied  with  oxygen  by  the  plant 
during  the  entire  pupal  period. 

The  common  painted  turtle  {Chrysemys  marginata)  and  the  snapping 
turtle  are  common  in  such  small  bays.  They  come  out  upon  the  logs  and 
bask  in  the  sun.  The  pied  billed  grebe  builds  its  floating  nest,  and  many 
other  aquatic  birds  feed  in  such  situations  (108). 

Characters  of  the  vegetation  formation:  This  formation  is  of  the 
old-pond  type  which  will  be  especially  discussed  in  the  following  chapter. 
There  are  two  characters,  one  or  the  other  of  which  is  possessed  by 
nearly  all  the  animals.  They  depend  upon  the  atmospheric  air  or  must 
have  the  support  of  the  vegetation,  or  both.  The  majority  of  the  ani- 
mals of  this  formation  stick  their  eggs  either  in  or  on  vegetation.     Such 


SUCCESSION  OF  COMMUNITIES  133 

formations  are  quite  similar  in  many  respects  to  the  formations  of  the 
\-egetation  in  sluggish  rivers  but  resist  lack  of  oxygen  and  stagnant 
water  much  better. 

d)  The  anaerobic  formation. — This  is  the  bottom  and  deep-water 
formation.  We  have  already  stated  that  the  circulation  of  water  (see 
Fig.  ID,  p.  61)  is  not  known  for  any  of  the  lakes  discussed.  Old  lakes  like 
those  about  Chicago  are  usually  covered  with  humus  on  the  bottom.  In 
this  humus  and  probably  just  above  it  there  is  little  or  no  oxygen. 
Analyses  of  the  bottom  water  from  ponds  with  humus-covered  bottoms 
showed  that  it  contained  no  oxygen.  The  open  water  of  the  lakes  with 
the  incomplete  circulation  in  summer  is  without  suflEicient  oxygen  to 
support  life,  below  the  level  of  circulation  (Fig.  11,  p.  61).  There 
are,  however,  numbers  of  animals  that  pass  the  summer  under  these 
conditions  (no,  in).  These  are  protozoa  belonging  to  eleven  genera, 
worms  belonging  to  two  genera,  one  rotifer,  one  ostracod,  and  the  small 
bivalve  {Pisidium  idahoense).  Dr.  Juday  kept  these  animals  in  jars 
without  oxygen  and  observed  their  activities.  The  rotifer  was  always 
active.  The  ostracod  showed  little  activity,  and  the  bivalve  kept  its 
\'alve  closed,  showing  no  activity  whatever. 

There  are  occasional  midge  larvae  in  the  mud  of  such  bottoms,  but 
they  are  rare.  Some  of  these  have  haemaglobin  in  their  blood  and  are 
supposed  to  be  able  to  use  oxygen  when  it  is  present  in  the  minutest 
quantities.  In  the  open  oxygenless  water  there  are  phantom  larvae 
(Corethra)  which  are  able  to  carry  a  supply  of  oxygen  with  them  from 
the  surface. 

III.     Succession  in  Lakes 

The  general  tendency  of  succession  in  lakes  has  been  indicated.  The 
first  formation  is  the  bare-bottom  type,  which  is  locally  transformed  to 
the  vegetation  of  open-water  type.  This  usually  begins  in  the  protected 
situations  first;  the  bays  are  ecologically  oldest.  These  bays  pass 
rapidly  from  the  third  open-lake  type  to  the  bay  conditions.  When  such 
a  stage  has  been  reached  the  situations  that  have  a  less  degree  of  protec- 
tion from  waves  have  reached  the  second  stage  and  we  have  lakes  as  we 
find  most  of  the  larger  ones  about  Chicago.  They  contain,  at  various 
points,  the  three  formations  which  we  have  discussed.  The  lake  is 
reduced  in  size  by  filling  near  its  shores  and  the  lowering  of  its  outlet. 
The  older  stages  are  continuously  encroaching  on  the  younger.  The 
area  of  barren  shoal  is  constantly  becoming  less  as  the  lake  fills  and  the 
outlet,  if  it  has  one,  is  lowered.  Around  the  shores  the  development  of 
prairie  or  forest  is  usually  well  begun  and  one  or  the  other  of  these  types 
of  land  vegetation  finally  displaces  the  lake. 


134  COMMUNITIES  OF  SMALL  LAKES 

I.      THE  INFLUENCE   OF   SIZE   AND   DEPTH 

Size  and  depth  have  a  marked  influence  on  the  rate  of  succession. 
If  the  lake  is  large,  like  Lake  Michigan,  its  waves  beat  upon  the  shores 
with  such  force  as  to  prevent  the  development  of  vegetation  or  the 
establishment  of  any  of  the  formations  just  discussed.  Smaller  lakes 
have  proportionally  less  efl&cient  wave-action,  and  situations  which  would 
not  be  protected  to  any  marked  degree  in  a  lake  like  Lake  Michigan  are 
relatively  free  from  effective  wave-action.  The  formations  succeed  one 
another  rapidly  where  wave-action  is  slight.  The  various  parts  of  the 
shore  of  a  small  kettle-hole  with  a  regular  shore-line  would  pass  through  all 
these  stages  at  nearly  the  same  rate.  Depth  is  an  important  factor  also 
because  the  various  formations  cannot  succeed  over  the  deep  water  until 
the  deeper  parts  are  filled  (or  drained),  which  often  requires  long  periods. 
The  rate  of  succession  in  lakes  is  then  directly  proportional  to  their  size 
and  depth.  The  small  lakes  pass  through  all  the  stages  more  quickly 
than  the  larger  lakes.  Those  considered  here  have  for  the  most  part,  at 
present,  become  dominated  by  the  late  stages.  The  lakes  of  the  inland 
type  which  are  large  enough  to  maintain  all  the  formations  discussed  are 
among  the  most  complex  of  all  our  habitats. 

2.      INFLUENCE   OF   MATERIAL   AND   MODE    OF   ORIGIN 

At  the  very  beginning  the  kind  of  material  in  which  a  lake  is  situated 
is  important  but  as  time  goes  on  it  becomes  less  and  less  important.  If 
the  lake  is  in  clay,  at  the  outset  there  are  no  sandy  areas,  but  the  action 
of  the  weaves  soon  removes  the  finer  material  and  leaves  sand  (the  finer 
materials  being  deposited  on  the  bottom  of  the  lake).  Young  lakes  in 
rock  are  probably  very  different  from  those  in  clay,  but  even  here  sandy 
shores  are  soon  formed  and  occupied  by  the  same  animals  as  sandy 
shores  of  different  origin. 

The  distinction  between  lakes  and  ponds  is  a  purely  artificial  one. 
The  ponds  have  the  same  communities  at  the  outset  as  the  lakes,  but 
the  changes  proceed  so  rapidly  that  very  young  ponds  are  rare.  All 
lakes  and  ponds  tend  to  become  ecologically  similar,  regardless  of  mode 
of  origin  and  kind  of  material. 

LIST  II 
The  following  Entomosiraca  have  been  taken  from  Wolf  Lake:  *  indicates  the 
species  is  found  in  Fox  Lake;  f  in  Butler's  Lake;  %  in  the  series  of  ponds  at  the 
head  of  Lake  Michigan:  Copepods:  X*\  Cyclops  serrulaius  Fischer;  *tJ  C.  albidiis 
Jurine;  JC.  vlridis  bremspinosus  Herrick.  Cladocerans:  Acropcrus  harpae  Baird; 
%  Scapholeberis  miicronata  Muel.;  %  Pleuroxus  denticidalus  Birge;  Diaphanosoma 
brachyuruni  Liev.;  %  Chydorus  sphaericus  Muel.;  Polyphemus  pedicidus  Linn;  Macrothrix 
ro^ea  Jurine;  XCcriodaplmia  reticulata  Jurine;  % Simocephalus serridatus  Koch;  Bosmina 
obtusirostris  Sars.     Ostracods:  Potamocypris  smaragdina  Vav. 


SMALL  LAKE  ANIMALS 


135 


•  TABLE  XXVI 

Animals  from  Small  Lakes 
Meaning  of  letters  occurring  in  the  columns  is  as  follows:     "Habitat"  column: 
S  =  bottomof  sand;  SH  =  bottom  of  sand  and  humus;  B  =  bulrush  vegetation;  V0  = 
vegetation  of  open  water;    VB  =  vegetation  of  bays;    in  "Lake  Where  Recorded" 
column:  F  =  Fox  Lake;  W= Wolf  Lake;  G= Lake  George;  B  =  Butler's  Lake 


Common  Name 


Scientific  Name 


Habitat  from 
Which  CoUected 


Caddis-worm 

Caddis-worm 

Caddis-worm 

Snail 

Snail 

Craj^h 

Turtle  (musk) 

Geographic  turtle 

Straw-colored  minnow. 

Johnny  darter 

Mussel 

Planarian 

Mussel 

Mussel 

Polyzoan 

Leech 

Brook  silverside 

Snail 

Snail 

Midges 

Amphipod 

May-fly  nymph '' 

Dragon-fly  njTnph . 

Polyzoan 

Shrimp 

Cricket-frog 

Top  minnow 

Snail 

Snail 

Snail , 

Damsel-fly  n3rmph .  . 
Dragon-fly  nymph .  . 
Dragon-fly  nymph .  . 

Back -swimmer 

Back-swimmer 

Back-swimmer 

Back -swimmer 

Leech 

May-fly *. . . 

Isopod 

Bug 

Beetle 

Beetle 


Goera  sp 

Molanna  sp 

Polycentropidae 

Pleurocera  subulare  Lea 

Goniohasis  livescens  Mke 

Camhariis  virilis  Hag 

Aromochelys  odorata  Lat 

Graptemys  gcographicus  LeS .  . 

Notropis  blennius  Gir 

Boleosoma  nigrum  Raf 

Lampsilis  luteola  Lam 

Planar ia  maculata  Leidy. .... 

Anodonta  grandis  Say 

A  nodonla  marginata  Say 

Plumatella  polymorpha  Kraep 

Placohdella  parasitica  Say. ... 

Labidesthes  siccidus  Cope .... 

Ancylus  fuscus  Adams 

Segmentina  armigera  Say.  .  .  . 

Chironomus  sp 

Hyalella  knickerbockeri  Bate. . 

Callibaetis  sp 

Ischnura  verticalis  Say 

Pectinatella  magnifica  Leidy. . 
Palaemonetes  paludosus  Gib .  . 

Acris  grylliis  Lee 

Fundidus  dispar  Ag 

Physa  gyrina  Say 

Planorbis  campanulatus  Say. . 

Planorbis  parvus  Say 

Enallagma  sp 

Tetragoneiiria  cynosura  Say .  . 

Anax  Junius  Dru 

Buenoa  platycnemis  Fieb 

Notonecta  variabilis  Fieb 

Plea  slriola  Fab 

Notonecta  itndulata  Say 

Macrobdella  decora  Say 

Ephemerella  excrucians  Walsh 
Mancasellus  danielsi  Rich. .  .  . 

Zaitha  fluminea  Say 

Coptotomus  inlerrogalus  Fab. . 
Donacia  sp 


S 
S 
S 
S 
S 
S 

;  S 
s 
s 
s 

S,SH,B 
S,SH 

s- 

s 

S,SH 

S,SH 

S,SH,B 

B 

B 

B 

B 

B 


Lake  Where 
Recorded 


vo 
vo 
vo 
vo 
vo 

VO,VB 
VO,VB 
VO,VB 
VO,VB 
VO.VB 

VB 

VB 

VB 

VB 

VB 

VB 

VB 

VB 

VB 

VB 

VB 

VB 

VB 

VB 

VB 

VB 


W 

F 

W 
W 
W 
W 
W 
W 
W,F 
W,F 

W,F 
W 


W 

W,F 
W,F 

W,F 
W 
W 
W 
W 
W 
W 
F 

W 
F 

W 
F 
F 
F 
W 
W 
F 


W 


CHAPTER  VIII 

ANIMAL  COMMUNITIES  OF  PONDS 

I.    Introduction 

Ponds  are  fascinating  to  all,  and  do  not  lack  interest  from  the  scien- 
tific point  of  view.  They  are  of  especial  interest  to  those  familiar  with 
the  laboratory  study  of  zoology.  The  common  animals  of  the  laboratory 
are  pond  animals,  because  pond  animals  are  forms  that  will  live  in 
stagnant  water.  The  common  aquarium  fishes  are  all  pond  fishes,  as 
the  brook  forms  die  quickly  if  they  are  not  supplied  with  running  water. 
The  frog,  so  much  studied,  is  a  pond  form.  The  conditions  in  ponds  are 
different  from  those  in  lakes  and  streams,  because  currents  are  not  strong 
nor  particularly  important.  The  water  doubtless  piles  up  at  one  side 
or  end  of  a  pond  during  strong  winds,  and  a  complete  circulation  is 
effected,  but  this  is  not  important.  All  of  the  conditions  of  lakes  are 
duplicated  in  ponds,  but  on  a  smaller  scale.  One  of  the  chief  differences 
between  ponds  and  lakes  is  the  vegetation.  Ponds  are  usually  very 
largely  captured  by  vegetation  which  is  very  much  like  that  in  the  bays 
of  lakes.  Succession  of  plants  in  ponds  is  similar  to  that  in  lakes;  the 
age  of  a  pond  is  therefore  a  matter  of  first  importance.  The  bottom 
materials  are  of  most  importance  at  the  beginning  (6,  112).  The  bottom 
materials  in  the  ponds  of  the  Chicago  area  are  rock,  clay,  and  sand. 
Rock-bottomed  ponds  have  been  but  little  studied,  though  there  are  a 
number  of  ponds  in  abandoned  quarries  of  different  ages  which  would 
make  a  good  series  for  investigation.  Clay  bottom  occurs  in  the  moraine 
area.  Nearly  all  the  natural  clay-bottomed  ponds  have  reached  a  stage 
at  which  the  bottom  is  not  important,  but  one  could  no  doubt  find  a 
good  series  if  he  were  to  make  a  special  study.  Sand-bottomed  ponds 
are  the  commonest  of  all,  and  for  the  purpose  of  studying  the  effect  of 
age  upon  ponds,  a  series  of  sandy-bottomed  ponds,  which  differed  chiefly 
in  the  matter  of  age,  was  selected. 

II.    Area  of  Special  Study 

The  ponds  that  have  been  made  the  subject  of  special  study  lie  in 
the  sand  area  at  the  south  end  of  Lake  Michigan,  within  the  corporate 
limits  of  the  city  of  Gary,  Ind.  They  may  be  reached  from  the  stations 
known  as  Pine,  Clark  Junction,  and  Buffington  (Fig.  84).     The  locality 

136 


ORIGIN  OF  PONDS 


137 


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138 


POND  COMMUNITIES 


is  characterized  by  a  series  of  ridges  running  parallel  with  the  shores  of 
the  lake.  Their  average  width  is  about  30  meters  (100  ft.),  and  they  are 
separated  by  ponds  somewhat  narrower.  Most  of  the  ponds  are  several 
miles  long  and  vary  in  depth,  during  the  spring  high  water,  from  a  few 
inches  to  4  or  5  ft.  Originally  there  were  probably  a  number  of  outlets 
to  the  ponds,  either  connecting  them  with  the  lake  or  with  the  Calumet 
River.  This  river  flows  across  the  long  ponds  at  a  small  angle.  The 
ponds  and  ridges  were  formed  under  water,  and  the  river  has  cut  its 
way  across  them  with  the  falling  of  the  lake  level.  The  building  of 
sewers  associated  with  the  growth  of  the  Northern  Indiana  towns  has 
drained  a  number  of  the  ponds,  and  roads  and  railroads  have  isolated 
parts  of  others. 

I.      ORIGIN   or   THE   PONDS    (62) 

The  waters  of  the  lake  appear  to  have  fallen  gradually  from  the  12-ft. 
level  referred  to  on  p.  47.  There  are  at  present  usually  two  or  three 
depressions  along  the  shore  of  the  lake  under  the  water.  The  present 
submerged  depressions  and  ridges  appear  to  be  strictly  comparable 
to  those  found  on  the  plain  of  Lake  Chicago,  and  the  ones  with  which 
we  have  to  deal  probably  belong  to  a  series  formed  by  the  continuous 
recession  of  the  lake  level  (Fig.  83).  This  gives  us  a  series  of  ponds 
differing  principally  in  age,  the  oldest  being  farthest  from,  and  the 
youngest  nearest  to,  the  lake. 

As  has  been  stated,  the  ponds  have  been  partly  drained,  so  that  we 
have  been  obliged  to  study  isolated  portions.  The  younger  members 
of  the  series  (ist,  5th,  7th,  and  14th,  as  counted  from  the  lake)  show  the 
greatest  differences  and  have,  accordingly,  been  studied  in  detail.  The 
arrangement  of  these  ponds  is  shown  in  Fig.  83.  In  addition  to  the 
ponds  named,  the  13th,  the  52d,  the  93d,  and  the  95th  have  been 
studied,  but  with  less  care. 

2.      PHYSICAL   CHARACTERISTICS    (112) 

The  main  facts  of  the  topography  of  the  isolated  portions  studied 
are  shown  in  Table  XXVIa. 

TABLE  XXVIa 


Pond 

Area  in  Sq.  M. 

Depth  in  Meters 

Average  Depth 

Slope  3-7° 

Slope  20° 

I 

3,500 

3,500 

25,000 

10,000 

50,000 

630 

0.6 

0.9 

0.9 

0.667 

O-S 

0.4 

0.3 
0.5 
O-S 
0.4 
0.2 
O.I 

Much 
Less 

Very  little 
Very  little 
Very  little 
Ver>^  little 

Little 

c 

Much 

7 

Much 

14. 

All 

20 

AH 

C2 

All 

ORIGIN  OF  PONDS 


139 


I40  POND  COMMUNITIES 

A  decrease  in  depth,  due  to  the  accumulation  of  humus  and  the  lowering 
of  the  ground-water  level,  is  to  be  noted  in  the  older  ponds.  The  series 
is,  then,  an  ecological  age-series,  and  throughout  our  discussion  we  refer 
to  earlier  and  later  phases  of  the  various  associations  concerned. 

III.     Communities  of  Ponds 

I.      THE   PELAGIC   FORMATION 

We  have  in  the  ponds  a  pelagic  formation.  Though  it  is  limited 
in  number  of  species,  many  of  which  breed  on  the  bottom,  it  is  similar 
to  that  of  larger  lakes.  We  have  found  little  difiference  in  the  pelagic 
species  inhabiting  younger  and  older  permanent  ponds.  Diaptomus 
reighardi  has  not  been  taken  from  ponds  filled  with  the  vegetation 
which  reaches  the  surface.  Other  species  are  about  the  same  in 
the  different  permanent  ponds.  The  pelagic  formation  is  poorly 
developed. 

2.      PIONEER   FORMATION    (TERRIGENOUS    BOTTOM) 

(Ponds,  I,  5,  7)  (113)  (Stations  9  and  32;  Tables  XXVII  and  XXXIV) 
The  youngest  ponds  of  the  Chicago  area  are  near  Waukegan.  The 
outer  end  of  the  Dead  River  receives  the  force  of  the  winter  waves  from 
the  lake  and  the  bottom  is  bare,  with  a  few  scattered  aquatic  plants. 
Here  animals  are  few.  We  have  taken  only  a  few  invertebrates.  The 
fish  present  probably  get  their  food  from  the  older  parts  farther  back 
from  the  lake.  The  fish  are:  the  pike  {Esox  lucius)  which  prefers  clear, 
clean,  cool  water  (79);  the  red-horse  {Moxostoma  aureolum)  which  dies 
in  the  aquarium  if  the  water  is  the  least  bit  impure,  and  which  also  suc- 
cumbs to  any  impurities  in  its  natural  environment  (79);  Notropis 
cayuga,  which  prefers  clear  waters;  the  common  shiner  {Notropis 
cornutus)  which  breeds  on  bare  bottom  (105),  and  the  white  crappie 
{Pomoxis  annularis)  which  lives  in  streams.  On  the  bottom  at  such  a 
period  one  is  likely  to  find  the  larvae  of  caddis-flies  {Goera  sp.),  snails, 
mussels,  etc.,  but  we  have  found  none  in  the  Dead  River. 

Vegetation  quickly  captures  parts  of  such  a  pond.  Chara  is  the 
first  plant  to  cover  parts  of  the  bottom.  After  this  has  happened,  the 
pioneer  formation  may  still  continue.  In  Pond  i  of  the  series  of  special 
study  (Fig.  85)  we  have  a  considerable  area  of  bare  sand,  and  the  forms 
present  are  the  caddis- worm  {Goera  sp.)  and  the  mussels  {Anodonta 
marginata  and  grandis,  and  Lampsilis  luteola).  These  are  preyed  upon 
by  muskrats  (Fig.  86).     There  are  a  number  of  fish  that  belong  to  this 


PIONEER  COMMUNITIES 


141 


formation  because  of  their  breeding  relations.  The  large-mouthed 
black  bass,  the  bluegill,  the  pumpkin-seed,  and  the  speckled  bullhead 
all  make  nests  on  the  sand,  the  male  fish  guarding  the  nests  and  driving 
off  other  fish  that  approach.  These  species  are  the  same  as  those  of  the 
bare-bottom  formations  of  a  lake.  In  their  feeding  the  fish  belong  in 
part  to  another  formation  in  the  pond,  namely,  that  of  the  chara. 

Character  of  the  formation :  The  formation  may  be  designated  as  the 
bare-bottom  formation,  the  forms  present  being  those  that  are  dependent 


Fig.  85. — Shows  Pond  i  at  the  extreme  low  water  of  the  drought  of  1908.  In  the 
-spring  the  old  boat  is  usually  covered  with  water.  In  the  foreground  a  large  area  of 
bare  sand  bottom  is  shown;  to  the  right  a  few  rushes  and  sedges.  The  absence  of 
shrubs  near  the  water's  edge  should  be  noted. 

upon  bare  bottom  in  their  most  important  activities— the  fish  in  breeding, 
the  caddis-worms  in  making  their  cases,  the  mussels  in  their  general 
activities.  It  is  necessary  for  the  mussels  to  be  on  bare  bottom  in  order 
to  maintain  themselves  in  an  upright  position. 

Tendencies  in  the  formation:  This  formation  is  similar  to  that  of  the 
bare  bottom  of  lakes.  The  vegetation  comes  in,  as  has  been  indicated  in 
the  protected  situations,  and  the  bare  bottom  disappears,  its  place  being 
taken  by  the  chara.     The  chara  gives  rise  to  humus,  upon  which  chara 


142  POND  COMMUNITIES 

will  grow  for  a  long  time,  so  the  bottom  becomes  a  humus-  and  chara- 
covered  bottom. 

-    3.       THE   SUBMERGED   VEGETATION   ASSOCIATION 

(Ponds  I,  5,  and  7;  Stations  32,  33,  and  34) 
The  Chara  community  is  entirely  different  from  that  of  the  bare 
bottom,  and  differs  also  from  that  of  other  vegetations.  Chara  is  highly 
siliceous.  It  is  probably  eaten  only  accidentally  by  animals  or  at  least 
forms  no  important  part  of  their  food.  It  should  be  considered  simply  as 
a  covering  for  the  bottom  and  a  resting-  and  living-place  for  animals. 
Some  fish  culturists  (113)  have  said  that  it  is  very  rich  in  life.  This 
may  be  true  under  certain  artificial  pond  conditions;  but  the  chara 
ponds  are  poorer  than  any  others  of  our  series.  Chara  differs  from  some 
other  plants  in  not  reaching  to  the  surface  of  the  water.  Many  aquatic 
insects  that  carry  air  beneath  the  surface  must  cling  to  objects  which 
reach  the  surface  when  obtaining  a  fresh  supply,  and  others  must  crawl 
to  the  surface  on  some  object  in  order  to  emerge  from  the  nymphal  skin 
(96).  Associated  with  chara  are  often  growths  of  bulrushes  near  the 
sides  of  the  ponds  and  on  the  sterile  bottom.  In  the  sparse  chara  the 
most  characteristic  animal  forms  are  Anodonta  grandis footiana  (Fig.  86), 
and  the  musk  turtle  {Aromochelys  odorata),  which  is  abundant  on  these 
bottoms  but  is  not  found  elsewhere.  There  are  often  nests  of  a  few  un- 
identified fishes  that  clear  off  the  bottom  in  building.  The  burrowing 
dragon-fly  nymph  (Fig.  87)  lives  on  the  bottom  among  sparse  chara,  in 
the  presence  of  but  little  oxygen.  It  lies  half  buried  in  the  mud,  with  its 
abdomen  protruding  a  little  at  the  end.  The  mud  minnow  {Umbra  limi) 
(Fig.  88),  the  golden  shiner  {Abramis  crysoleucas)  (Fig.  88),  the  chub- 
sucker  {Erimyzon  sucetta),  bullheads,  the  little  pickerel  (Esox  vermicula- 
lus),  the  tadpole  cat  {Schilbeodes  gyrinus),  and  occasionally  the  warmouth 
bass  {Chaenobryttus  gulosus)  spend  their  time  in  the  denser  chara.  The 
shiner  and  mud  minnow  place  their  eggs  on  the  chara  or  other  plants. 

Among  the  most  abundant  forms  in  the  association  are  the  midge 
larvae  (Chironomus);  these  (Figs.  89,  90,  91)  are  present  sticking  to  the 
vegetation  in  their  small  silken  cases  in  great  numbers  (81).  They  are 
important  articles  in  the  food  of  the  fishes.  Aquatic  insects  are  not 
numerous  except  for  the  midge  larvae  and  a  little  May-fly.  Others 
are  occasional  horseflies  (Fig.  92),  damsel-fly  nymphs,  May- fly  nymphs 
{Siphlurus  sp.),  and  occasional  dragon-fly  nymphs  {Tramea,  Anax, 
Leucorhinia) .  There  are  also  a  number  of  dytiscid  beetles,  many  of 
which  are  common  in  all  shallow  waters,  even  rain  pools,  because  of 
their  powers  of  flight. 


PIONEER  COMMUNITIES 


143 


Ecologically  one  of  the  most  interesting  insects  is  a  caddis-worm 
{Leptoceridae),  which  creeps  over  the  Char  a  and  submerged  wood. 
It  (Fig.  93)  has  a  case  made  of  the  minutest  sand  grains  and  pieces  of 
humus,  such  as  are  stirred  up  by  the  waves  and  which  are  to  be  found 


Representatives  of  a  Youxg  Pond  Community 

Fig.  86. — The  shell  of  a  mussel  (Anodonla  grandis  footiana)  that  has  been  broken 
open  by  a  muskrat;  slightly  enlarged. 

Fig.  87.— The  burrowing  dragon-fly  nymph  {Gomphus  spicatiis),  with  the  mask 
extended. 

Fig.  88. — Some  fishes  of  the  pond.  The  dark  fish  which  rests  near  the  bottom  is 
the  mud  minnow  {Umbra  limi).  The  fish  swimming  about  is  the  golden  shiner 
{Abramis  crysoleucas) ;  1/5  natural  size. 


among  the  chara.  This  species  is  the  successor  of  the  bottom  species 
(Goera).  It  belongs  to  a  different  group  and  has  structural  characters 
which  distinguish  it  from  Goera,  but  which  probably  have  no  relation 
to  its  habitat  or  habits.  On  the  other  hand,  the  mores  as  indicated  by 
case-building  is  also  different  but  is  related  to  the  environment.     The 


144 


POND  COMMUNITIES 


crustaceans  constitute  an  important  element  in  this  association.  The 
smaller  amphipod  {Hyalella  knickerhockeri)  is  abundant  among  the 
chara.  The  crayfish  (Cambarus  immunis)  occurs  here  sparingly.  In 
ponds  there  is  an  important  element  of  small  crustaceans  that  belong 
to  the  vegetation  and  the  bottom;    this  element  is  composed  chiefly  of 


Representatives  of  the  Submerged  Vegetation  Association 

Figs.  89,  90,  91. — Larva  of  a  midge  (89),  pupa  of  the  same  (90),  the  adult. 
Midges  are  inhabitants  of  the  chara-covered  bottom;  enlarged  about  4  times  (after 
Johannsen,  Bull.  N.Y.  State  Museum). 

Fig.  92. — ^The  eggs  of  the  common  large  black  horsefly  on  the  tip  of  the  bulrush 
stalk. 

Fig.  93. — The  chara-inhabiting  caddis-worm  (Leptocerinae);  enlarged  as  indi- 
cated. 

Fig.  94. — Ostracod  {Notodromas  monacha  Miill.);  30  times  natural  size  (after 
Sharp) . 

Ostracoda  (Fig.  94),  which  are  small   bivalved  forms  resembling  the 
bivalved  MoUusca.     They  form  food  for  fishes  to  a  small  degree. 

Especially  abundant  just  under  the  chara  are  the  red  water-mites 
{Limnochares  aquaticus)  (Fig.  80,  p.  130).     One  sees  numbers  of  these 


PIONEER  COMMUNITIES  145 

when  he  stirs  the  bottom.  Creeping  over  the  plants  are  the  small 
snails  (Amnicola  limosa)  (Fig.  100,  p.  146).  These  respire  by  means 
of  gills.  Other  snails  are  also  occasionally  present.  Physa  and  Lym- 
naea,  etc.,  are  always  small  or  juvenile.  We  have  never  taken  an  adult 
specimen  of  these  from  the  young  ponds  and  in  all  only  a  few  specimens 
have  been  taken.  These  animals  get  into  the  ponds  that  are  formed  by 
the  removal  of  sand.  We  are  not  at  all  sure  but  that  the  few  forms 
found  in  Pond  i  are  the  result  of  such  entrance,  rather  than  the  regular 
establishment  of  the  species. 

Among  the  bulrushes  are  a  few  aquatic  insects  that  belong  to  the 
vegetation  that  comes  above  the  surface.  One  of  the  most  characteristic 
forms  is  the  neuropterous  larva  {Chauliodes  rastricornis)  (Figs,  no, 
III,  p.  150),  which  is  a  marsh  form  and  will  drown  in  water. 

Characters  of  the  association:  This  association  differs  from  the 
preceding  and  from  the  others  generally  in  being  distinctly  aquatic  and 
also  essentially  independent  of  the  bare  bottom  and  of  the  surface.  The 
animals  of  this  association  are,  however,  strictly  dependent  upon  the 
vegetation  for  nesting-places,  shelter,  etc.  The  mud  minnow  has  been 
studied  experimentally  and  shows  avoidance  of  direct  light. 

Tendencies  in  the  association:  This  association,  like  all  the  others,  is 
destined  not  to  last;  changes  are  taking  place  all  the  time.  The  chara 
is  filling  the  pond  at  the  rate  of  one  inch  a  year  (58)  and  is  making  a  fine 
soil  for  roots  of  other  plants.  As  soon  as  the  dense  chara  stage  has 
existed  for  a  time  we  find  other  plants,  such  as  Myriophyllum,  Pota- 
mogeton,  and  water-lilies.  As  soon  as  these  have  become  established  we 
have  the  commencement  of  the  next  association.  These  plants  usually 
appear  in  spots,  and  in  many  cases  the  zones  are  much  less  important 
than  in  the  lakes  because  of  the  small  areas  of  the  plants.  We  can, 
however,  recognize  a  zone  of  water-lilies,  and  zones  or  patches  of  other 
plants. 

Just  as  we  noted  that  the  formations  of  the  bare-bottom  type  existed 
in  the  small  ponds  with  the  Chara,  we  see  also  that  the  surface-reaching 
vegetation  occurs  with  the  Chara  association  and  often  all  three  occur 
together.  Pond  5  contains  a  poorly  developed  phase  of  all  three,  the 
bare  bottom  being  of  minor  importance.  Pond  7  contains  the  chara 
association  and  the  surface-reaching  association.  Ponds  14  and  30  are 
the  best  expressions  of  the  surface- reaching  type,  and  Pond  52  is 
the  last  stage  of  it.  This  will  be  discussed  more  fully,  and  we  will 
pass  directly  to  the  association  of  the  vegetation  which  reaches  the 
surface. 


146 


POND  COMMUNITIES 


3.      THE   ASSOCIATION   OF  EMERGING  VEGETATION 

(Stations  34-37.  39;  Ponds  5,  7,  and  14)   (Fig.  loi)  (30  and  52) 
With  the  incoming  of  the  water-lilies  and  the  fine-leafed  plants,  we 
have  the  inauguration  of  a  new  state  of  affairs.     Among  the  new  animals 


_L    T    n 


Representatives  of  the  Dense  Bulrush  Association  (Pond  5) 
(All  about  natural  size) 

Fig.  95. — The  common  diving  spider  (Dolomedes  sexpunctatus).  The  individual 
from  which  this  drawing  was  made  was  taken  with  a  nymph  of  the  dragonfly  shown, 
in  its  jaws. 

Figs.  96,  97,  98. — Various  stages  of  a  dragon-fly  {Leucorhinia  inlacta)  \  96,  nymph ; 
97,  about  to  shed  its  outer  covering;  98,  the  adult.     (Modified  from  Needham.) 

Fig.  99. — The  larva  of  a  caddis- worm  (Phryganeidae),  which  makes  its  case  from 
bits  of  grass  blades,  etc. 

Fig.  too. — Small  gill-breathing  snail  {Amnicola  limosa). 

that  come  in,  the  bivalved  moUusks  deserve  special  mention.  The 
Unionidae  must  have  bare  bottom  for  their  activities;  they  are  too  large 
and  heavy  to  climb  on  such  small  vegetation,  and  the  development  of 
such  a  habit  has  not  taken  place.     They  disappear  with  the  sparse 


MATURE  COMMUNITIES 


147 


Char  a.  Their  place  is  taken  by  other  bivalves,  viz.,  the  Sphaeridae,  such 
as  Musculium  partumeium,  which  lives  in  the  humus  of  the  bottom,  and 
Musculium  secure  and  truncatum,  which  live  in  the  vegetation  and  are 
able  to  climb  on  the  vegetation  and  on  the  side  of  aquarium  jars. 

In  the  early  phases,  shrubs  and  young  trees  have  begun  to  grow  by  the 
sides  of  the  ponds  and  these  from  time  to  time  fall  into  the  water,  thus 
forming  a  resting-place  for  many  forms  that  are  not  found  in  the  other 
situations.     Diving  spiders  (Fig.  95)  are  common  on  the  bulrushes  which 


Fig.  ioi. — Showing  Pond  14  at  moderate  low  water.  In  contrast  with  Pond  i 
we  see  that  it  is  choked  with  emerging  vegetation  and  the  margin  occupied  by  shrubs 
and  bulrushes,  etc. 


are  here  growing  on  a  bottom  of  humus  outside  leaf-bearing  plants 
(Fig.  ioi),  inside  the  shrubs.  These  spiders  dive  for  the  immature 
aquatic  insects  which  are  here  at  their  maximum.  We  find  numerous 
damsel-fly  nymphs  and  dragon-fly  nymphs,  both  the  creeping  form  {Leu- 
corhinia  intacta)  (Figs.  96,  97,  98)  and  the  climbing  form.  The  burrow- 
ing dragon-fly  nymph  has  gone,  or  is  present  in  small  numbers  only,  and 
there  are  but  few  May-fly  nymphs.  Those  that  persist  creep  about  on 
submerged  sticks  in  company  with  Amnicola  and  are  especially  likely  to 
occur  in  the  earlier  phases  of  this  community.     With  these  occur  the 


148  POND  COMMUNITIES 

caddis- worms  {Phryganeidae:  Neuronia)  (Fig.  99),  which  are  also  abun- 
dant in  the  later  stages  of  dense  vegetation.  This  worm's  case  is  some- 
what similar  in  form  to  that  of  Leptoceridae,  being  a  circular  tube,  but  it 
is  made  of  pieces  of  grass  blades  or  other  pieces  of  plant  fragments  instead 
of  sand  grains.  The  pieces  are  fastened  together  with  silk.  The  worm  is 
found  creeping  among  the  vegetation,  drawing  its  case  after  it.  Amnicola 
(Fig.  100),  the  river-dwelling  snail,  is  common,  especially  on  twigs  and 
logs.  In  the  mature  stage  represented  by  Pond  14  (Fig.  loi)  the  com- 
mon newt  (Fig.  102)  probably  reaches  its  maximum  abundance.  The 
snails  which  are  at  best  advantage  in  these  ponds  are  the  lung  breathers. 
They  can  here  come  to  the  surface  for  air,  and  food  is  abundant,  as  the 
surfaces  of  the  plants  are  covered  with  algae  and  these  form  the  food  of 
the  snails.  Those  snails  which  come  to  the  surface  for  air  are  common. 
Planorhis  campanulatus  (Fig.  103)  is  characteristic  of  the  mature  stage 
and  Lymnaea  reflexa  (Fig.  104)  in  the  older  stages.  The  individuals  in 
this  case  are  larger  than  those  of  the  temporary  marshes  (cf.  Figs.  104 
and  125,  pp.  149, 175).  Planorhis  parvus  (Fig.  105)  is  commonest  in  the 
earliest  phases  and  Planorhis  hirsutus  (Fig.  106)  in  the  later.  Diving 
beetles  (Fig.  107),  which  are  common  throughout,  are  most  numerous 
in  the  denser  vegetation.  The  soldier-fly  larvae  (Fig.  108)  are  often 
common  in  the  dense  filamentous  algae  of  the  mature  phases  of  the  asso- 
ciation; here  the  number  of  all  dipterous  larvae  is  greater  than  at  any 
other  point.  Midge  larvae  occur  in  great  numbers,  having  their  cases 
among  the  algae.  Horseflies  (Fig.  92),  also  Tony  pus,  Ceratopogon,  and 
some  mosquitoes  are  present.  Specific  identification,  however,  is  not 
possible,  and  whether  or  not  the  species  differ  in  modes  of  life  or  reactions 
from  those  inhabiting  the  earlier  stages  in  the  pond  series  has  not  been 
determined. 

Adult  aquatic  insects  have  increased  with  the  increase  in  vegetation, 
in  a  remarkable  fashion.  The  prominent  forms  are  the  larger  bugs,  such 
as  the  electric-light  bugs  (Zaitha  fluminea  and  Belostoma  americana 
Leidy,  with  Benacus  griseus  Say).  The  water-boatmen  are  also  common. 
The  species  of  these  are  not  well  known,  and  we  cannot  say  whether  or 
not  they  are  the  same  in  the  older  and  younger  ponds.  Back-swimmers 
are  also  abundant  {Nolonecta  variabilis  and  undulata,  Biienoa  platycnemis, 
and  the  small  form.  Plea  striola,  occur  here).  They  are  few  in  number 
or  absent  from  the  younger  ponds. 

Some  animals  particularly  abundant  in  the  older  stage  are  the 
common  leech  (Placohdella  parasitica)  (Fig.  109),  the  larvae  of  a  netted- 
winged  insect  (Chauliodes  rastricornis)  (Figs,  no,  in),  the  large  flat 


MATURE  COMMUNITIES 


149 


snail  (Planorbis  tr holms)  (Fig.  112),  and  the  amphipod  {Eucrangonyx 
gracilis)  (Fig.  113).  All  these  occur  in  the  senescent  stage,  where  in 
dry  years  the  pond  goes  almost  dry.  The  vertebrates  of  the  mature 
and  later  stages  are  not  numerous.  The  fish  are  limited  to  mud-  and 
muck-preferring  species,  the  black  bullhead  {Ameiurus  melas)  and  the 
mud  minnow  {Umbra  limi)  (106).  The  grass  pickerel  and  the  dogfish 
are  found  in  such  \egetation-choked  ponds. 


Representatives  of  the  Emerging  Vegetation  Association  (Pond  14) 

Fig.  102. — The  common  newt  {Diemictylus  viridescens);  natural  size  (after  Hay). 

Fig.  103. — A  flat  pond  snail  {Planorbis  campanulatus);  natural  size. 

Fig.  104. — The  common  pond  snail  (Lymnaea  reflexa);  natural  size. 

Fig.  105. — Small  flat  snail  {Planorbis  parvus);  3  times  natural  size. 

Fig.  106. — A  snail  {Planorbis  hirsutus);  3  times  natural  size. 

Fig.  107. — A  predaceous  diving  beetle  (Cybister  fimbriolatus  Say);  natural  size. 

Fig.  108. — A  soldier-fly  larva — unidentified;  twice  natural  size. 

The  amphibia  are  the  frogs  which  occur  in  all  stages  of  the  associa- 
tion, and  the  common  salamander  {Amblysloma  tigrinutn),  which  burrows 
in  the  soft  mud  where  it  remains  during  the  greater  part  of  the  year. 
It  comes  out  in  spring  (February  or  March)  and  deposits  eggs  in  the 
pond,  where  the  young  are  found  later.     Of  the  turtles  the  common 


I50 


POND  COMMUNITIES 


painted  turtle  {Chrysemys  marginata)  is  abundant,  basking  on  the  fallen 
trees.  The  geographic  turtle  and  the  snapping  turtle  are  found  also 
in  the  younger  phases.  Garter-snakes  pick  up  their  food  along  the 
ponds  (Fig.  114),  while  muskrats,  occasional  minks,  and  various  acjuatic 
birds  (108)  feed  in  the  ponds. 


Senescent  Pond  Inhabitants 

Fig.  109. — A  leech  with  young  attached  to  the  ventral  side  {Placobdelhi  para- 
sitica) ;  natural  size. 

Fig.  no. — The  larva  of  a  netted-winged  insect  (Cliauliodes  raslricornis). 

Fig.  III. — -Pupa  of  the  same  (slightly  enlarged). 

Fig.  T12. — A  smiil  {Planorbis  trivolvis);  natural  size. 

Fig.  113. — Common  amphipod  {Eucrangonyx  gracilis);  twice  natural  size. 

Fig.  114. — Pond  58  in  a  dry  season,  showing  dead  fish  (mud  minnows)  both 
on  bottom  and  out  of  water  and  in  the  water.  A  garter-snake  {Tharnnophis  sp.) 
feeding  on  the  fish. 

Consocies  of  logs. — This  is  the  chief  place  to  find  the  sponge  and  the 
polyzoa.     Their  numbers  vary  from  year  to  year  but  they  are  usually 


SUCCESSION  OF  COMMUNITIES  151 

present.  With  them  are  often  found  leeches,  especially  Macrohdella 
decora,  which  is  a  brilliant  red-and-green  form.  The  only  character- 
istic insect  is  the  dytiscid  beetle  {Agabus  semipunctatus  Kirby)  (99c) 
a  slender  reddish-brown  form.  The  other  forms  found  here  are  inci- 
dental in  the  vegetation.  Hollow  logs  are  probably  used  for  breeding- 
places  by  the  fishes,  such  as  the  bullheads  (105),  while  the  eggs  of  Physa 
and  of  water-mites,  and  some  of  the  aquatic  insects,  are  also  placed  here. 
The  mammals  of  these  ponds  are  the  muskrat,  which  occurs  in  all  the 
stages,  and  the  mink,  which  is  now  rare. 

Tendencies  of  the  association:  This  association  is  unstable.  Its 
fate  is  heralded  by  the  incoming  of  different  amphibious  plants  at  the 
sides.  This  is  the  form  Proserpinaca,  with  the  divided  leaves  above 
water  and  the  entire  ones  below.  This  is  often  associated  with  Equisetum 
and  plants  that  have  the  growth  form  of  grasses.  Following  these  are 
the  shrubs,  such  as  the  buttonbush  (6).  Before  these  have  captured 
the  entire  pond  it  becomes  dry  during  the  dry  season  and  the  end  of  the 
aquatic  community  is  come.  The  formation  which  follows  is  the  tempo- 
rary pond,  swamp,  or  marsh  type. 

Characters  of  the  formation:  The  formation  composed  of  the  two 
associations  mentioned  may  be  characterized  as  made  up  of  forms 
which  require  but  little  oxygen,  and  no  bare  bottom.  The  reproduction 
is  one  of  two  types:  either  the  young  are  carried  or  the  eggs  are  attached 
to  plants.  Some  of  those  carrying  the  young  are  the  Sphaeridae,  the 
amphipods,  and  the  isopods.  Those  sticking  the  eggs  onto  or  into  the 
vegetation  are  the  snails  (all),  the  Dytiscldae,  all  the  species  recorded,  the 
Hydro philidae,  the  Notonectidae,  the  Belostomidae,  the  Ranatras,\ht 
caddis-flies,  the  Donacias,  and  in  fact  most  of  the  forms  of  the  formation. 

IV.  Succession 
The  first  formation  to  take  possession  of  a  pond  when  it  is  first 
separated  from  a  lake  like  Lake  Michigan  is  the  bare-bottom  formation; 
chara  soon  makes  its  appearance  in  the  deeper  parts  and  we  have  the 
beginning  of  the  chara  association.  The  chara  association  so  acts  upon 
the  bottom  by  covering  it  with  humus  and  vegetation  that  it  renders 
the  continued  existence  of  the  bare-bottom  formation  impossible  (6, 
1 1 2,  1 14,  1 14a).  At  the  same  time  it  prepares  a  way  for  the  vegetatiori 
which  reaches  to  and  above  the  surface.  This,  in  turn,  fills  the  pond 
still  further,  and  the  strictly  marsh  vegetation  takes  possession.  The 
history  of  the  true  pond  is  then  at  an  end  and  the  story  of  the  marsh 
begins.     Our  series  of  95  ponds  illustrates  the  series  of  stages.     The 


152  POND  COMMUNITIES 

vegetation  which  comes  to  the  surface  of  the  water  and  the  later  marsh 
and  swamp  vegetation  encroach  from  the  sides  toward  the  center. 

Entornostraca  do  not  ordinarily  show  so  clear  a  succession  of  species 
as  do  other  groups  and  our  collections  are  very  incomplete.  The  follow- 
ing have  been  noted:  Cladocerans:  Ceriodaphnia  reticulata  Jurine,  C. 
pulchella  Sars,  and  C.  qiiadrangula  Muel.  from  Ponds  52  to  93. 
Copepods:  Cyclops  albidus  Jurine  appears  more  common  throughout 
the  series  and  C.  viridis  Jurine  is  common  in  the  older  ones.  Diaptomus 
reighardi  Marsh  is  in  the  younger  ponds  and  its  place  is  taken  by 
D.  leptopus  Forbes  beginning  with  Pond  30.  Of  the  ostracods,  Cypria 
exsculpta  Fisch.  is  common  throughout  the  series.  Cypridopsis  vidua 
MiiU.  is  common  in  the  semi-temporary  ponds. 

I.      FATE   OF   THE   PONDS 

In  the  late  stages  the  pond  dries  during  extreme  droughts  and  passes 
rapidly  from  the  stage  at  which  it  dries  occasionally  during  a  dry  season 
to  the  stage  when  it  dries  every  season.  It  is  then  known  as  a  marsh  or 
swamp,  or  often  vernal  marsh  or  swamp,  or  summer  dry  pond.  At  such 
a  stage  it  is  a  land  habitat  in  summer  and  a  water  habitat  in  spring.  As 
the  pond  bottom  is  built  up  higher  by  the  accumulation  of  peat,  and  the 
surrounding  ground- water  level  is  lowered  by  the  forces  of  erosion,  the 
question  of  w^hat  is  to  become  of  the  pond  brings  us  to  a  question  of  great 
importance  in  connection  with  climatic  formations.  It  will  become  what- 
ever the  surrounding  climatic  formation  may  be.  If  it  is  forest,  directly 
or  indirectly,  the  pond  becomes  forest,  and  if  it  is  steppe  the  pond  be- 
comes steppe,  while  if  prairie  or  savanna  the  pond  becomes  savanna. 

We  have  already  noticed  that  the  area  of  study  is  on  the  border  of 
the  forest  and  prairie  (steppe  formations).  A  pond  in  the  area  of  study 
may  therefore  become  prairie  or  forest.  Ponds  with  sloping  sides  usually 
become  prairie,  and  those  with  steep  abrupt  banks  or  shores  turn  into 
forest.  There  is  no  marked  difference  between  the  animal  life  of  the  two. 
Collections  made  in  a  series  of  three  prairie  ponds  which  are  situated 
near  Wolf  Lake,  Ind.,  and  which  in  ecological  age  may  be  compared  with 
Ponds  I,  7,  and  14  of  the  Lake  Michigan  series,  are  almost  parallel  with 
the  collections  from  the  Lake  Michigan  ponds.  The  differences  to  be 
noted  are  that  the  snail  Planorhis  trivolvis,  which  usually  occurs  in  old 
ponds  only,  is  found  in  the  earliest  pond  of  the  prairie  pond  series,  while 
the  snail  Vivipara  contectoides  and  the  shrimp  Palaemonetes  paludosus, 
which  usually  occur  only  in  streams  and  small  lakes,  also  occur  in  the 
prairie  pond  series.  The  presence  of  the  latter  two  may  be  explained,  how- 
ever, by  the  fact  that  the  ponds  were  once  connected  with  Wolf  Lake. 


POND  ANIMALS 


153 


In  the  pond  formation  proper,  the  fate  of  the  pond  early  becomes 
evident  along  the  margin.  This  will  be  discussed  in  connection  with 
swamps  and  marshes.  The  discussion  of  the  areas  properly  called 
marshes  and  swamps  is  the  most  complex  of  all  our  discussions,  and  will 
be  taken  up  in  the  chapter  on  swamps,  marshes,  and  temporary  ponds. 

Tables  XXVII-XXXIII  show  animals  recorded  from  the  series  of 
ponds  at  the  head  of  Lake  Michigan  (Stations  32-37). 

TABLE  XXVII 
Sponges 


Pond  Numbers 

I 

S 

7 

14 

30 

52 

93 

95 

Meyenia{?)  craterijonnis  Pot..  .  . 

Meyenia  flimatllis  Auct 

Heteromeyenia  argyrosperma  Pot . 
Spongilla  fragilis  Leidy 

* 

* 

* 
* 
He 

* 

TABLE  XXVIII 
Leeches 


Pond  Numbers 

I 

SC 

7<l 

14 

30 

52 

93 

95 

Glossiphonia  fusca  Castle 

* 
* 
* 

* 
* 

if 
* 

* 
* 

* 
* 

* 
* 

* 

* 
* 

* 

* 

* 
* 

* 

* 
? 

* 

* 
* 
* 

Dina  fervida  Verrill 

Erpobdella  punctata  Leidy 

Macrobdella  decora  Say 

Haemopis  graiidis  Verrill 

Placobdella  parasitica  Say 

Placobdella  rugosa  Verrill 

Glossiphonia  heteroclila  Linn 

Haemopis  marmoratis  Say 

TABLE  XXIX 

Sphaeridae  AND  Unionidae 


Name 

Pond  Numbers 

I 

SC         7a 

14b 

30 

52 

93 

95 

Unionidae— 

Lampsilis  luteola  Lam 

* 
* 
* 

* 
* 
* 

* 

* 

* 

* 
* 

? 

* 

* 

* 

? 

* 

* 
* 

Anodonta  grandis  Say 

Anodonta  marginata  Say 

Anodonta  grandis  footiana  Lea. . . 
Sphaeridae — 

Miisculium  truncalum  Lins 

Muscidium  secure  Prime 

Musculium  partumeium  Say 

154 


POND  COMMUNITIES 


TABLE  XXX 

Snails 


Name 


Pond  Numbers 


^a 

146 

30 

52 

93 

* 

* 

* 

* 

* 

♦ 

c 

C 

* 

C 

* 

* 

* 

* 

* 

* 

* 

* 

* 

• 
* 

• 

C 

* 

A 

A 

* 

« 

C 

* 

A 

? 

* 
* 

• 
* 

Amnicola — 

Amnicola  limosa  Say * 

Amnicola  cincinnatiensis  Lea.  .  .  . '     * 
Amnicola  limosa  parva  Lea 

Physa — 

Physa  gyrina  Say I     F 

Physa  heteroslropha  ?  Say 

Lymnaeidae — 

Lymnaea  reflexa  exilis  Lea 

Planorbis  bicarinatus  Say 

Lymnaea  humilis  modicella  Say. 

Lymnaea  ohrussa  Say I     * 

Planorbis  parvus  Say * 

Planorbis  campamdatiis  Say 1     * 

Planorbis  hirsiitus  Gld * 

Planorbis  exacuosus  Say j 

Lymnaea  reflexa  Say |     F  • 

Planorbis  defleclus  Say 

Planorbis  trivolvis  Say 

Segmentina  armigera  Say 


TABLE  XXXI 

Crustacea 


Pond  Numbers 

Name 

I 

SC 

7a 

146 

30 

52 

93 

95 

Hyalella  knickerbockeri  Bate 

Eucrangonyx  gracilis  Smith 

Mancasellus  danielsi  Rich 

Asellus  communis  Say   

c 

F 

C 
F 

F 

C 
C 

c 

F 

F 
A 

C 
F 

F 

A 

* 

* 

C 

? 

A 

* 

* 

A 

* 

* 

F 

* 

Cambarus  immunis  Hagen 

Cambarus  blandingi  acutus  Girard .  . 

* 

* 

* 

* 

POND  ANIMALS 

*  TABLE  XXXII 

Aquatic  Insect  Larvae  and- Nymphs 


15s 


Name 


Pond  Numbers 


146 


30 

52 

93 

■¥ 

* 

* 

* 

* 

* 

* 

* 
* 

* 

* 

* 

* 

* 

if 

A 

* 

* 

* 

* 

* 

* 

* 

* 

? 

* 

? 

* 

* 

* 

* 

? 

* 

May-flies — 

Siphlurns  sp 

Caenis  sp 

CaUibaelis  sp 

Neuroptera — 

Chauliodes  raslricornis  Ram  .  . 
Damsel-flies — 

Lestes  sp 

Enallagma  sp 

Ischmira  verticalis  Say 

Dragon-flies— 

Tramea  lacerata  Hagen 

Celithemis  eponina  Drury. ... 

Libellula  pulchellaDmry 

Gomphus  spicatus  Selys , 

Leucorhinia  intacta  Hagen .  .  . 

Anax  Junius  Drury 

Sympelrum  riibicmidulum  Say 

Sympelrum  sp 

Pachydiplax  longipennis  Burm 

Epiaeschna  heros  Fab 

Caddis-worms — 

Goera  sp 

Leptocerinae  sp 

Neuronia  sp 

Diptera  larvae — 

Chironomid  larvae 

Stratiomyid  larvae 

Tanypus  sp 

Tipulid  larvae 

Ceratopogon  sp 

Hemiptera — 

Ranalra  kirkaldyi  Buen 

Corixa  sp 

Ranatra  fusca  P.B 

Zaitha  fluminea  Say 

Notonecla  midnlata  Say 

Buenoa  plalycnemis  Fieb .  .  .  .  , 

Notonecla  variabilis  Fieb 

Plea  striola  Fieb 

Water-striders — 

Gerris  rufoscutellatus  Lat .... 

Gerris  marginalus  Say 

Mesovelia  bisignata  Uhl 


156 


POND  COMMUNITIES 


TABLE  XXXIII 
Distribution  of  Fish:    Ponds  Arranged  According  to  Ecological  Age 
For  meaning  of  numbers  and  letters  see  Fig.  84,  p.  139. 


Common  Name 


Large-mouthed  black  bass, 

Bluegill 

Blue-spotted  sunfish 

Pumpkin-seed 

Warmouth  bass 

Yellow  perch 

Chub-sucker 

Spotted  bullhead 

Pickerel 

Mud  minnow 

Golden  shiner 

Yellow  bullhead 

Black  bullhead 

Dogfish 


Scientific  Name 


Microplerus  salmoides .  . 

Lepomis  pallid  us 

Lepomis  cyanellus 

Eupomolis  gibbosiis .... 
Chaenobryttus  gulosits  .  . 

Perca  flavescens 

Erimyzon  siicetta 

Ameiurus  nebulosus .  . .  . 

Esox  vermiculatus 

Umbra  limi 

Abramis  crysoleucas. .  .  . 

Ameiurus  natalis 

Ameiurus  melas 

Amia  calva  (juvenile) .  . 


Ponds 


146 


TABLE  XXXIV 

Higher  Vertebrates 


Name 


Aromochelys  odor  at  a  Lat .  .  . 

Rana  pipiens  Sch 

Chrysemys  marginata  Ag .  .  . 
Graplemys  geographicus  LeS 
Diemictyliis  viridescens  Raf . 
Fiber  zibethicus  Linn 


Pond  Numbers 


14A 


CHAPTER  IX 
CONDITIONS  OF  EXISTENCE  OF  LAND  ANIMALS 
I.    Introduction 

Man  being  a  land  animal,  it  is  natural  that  he  should  be  more  familiar 
with  the  conditions  of  existence  of  land  animals  than  with  those  of  aquatic 
forms.  The  reader  will  recognize  that  the  primary  divisions  into  which 
land  animals  may  be  divided  are  (a)  those  living  exposed  to  the  atmos- 
phere on  the  surface  of  the  soil  and  of  plants  and  animals,  and  (b)  those 
out  of  direct  contact  with  the  atmosphere,  in  the  soil,  in  wood,  and  in  the 
tissues  of  living  plants  and  animals.  The  solid  substances  in  and  upon 
which  animals  live  are  called  materials  for  abode  (55, 115)  and,  aside  from 
soil,  materials  are  just  as  varied  as  are  the  living  and  decaying  bodies  of 
plants  and  animals.  For  this  reason,  an  adequate  discussion  of  such 
materials  for  abode  would  require  a  separate  treatise.  Since  the  laws 
governing  the  physical  conditions  surrounding  animals  living  hidden 
away,  for  example  in  the  bodies  of  living  and  dead  organisms,  are  little 
known,  we  will  pass  directly  to  a  discussion  of  the  conditions  of  existence 
of  animals  living  in  soil  and  exposed  to  atmosphere. 

11.     Soil  (116) 

Because  of  its  importance  in  agriculture,  the  relation  of  plants  to  soils 
has  been  much  studied.  The  laws  governing  plants  in  their  relation 
to  soils  apply  in  the  main  to  soil-inhabiting  animals,  all  the  various 
properties  of  soils  being  of  some  importance  in  this  connection. 

I.      TEXTURE 

The  texture  of  soils  is  of  importance  to  animals  because  of  the  vary- 
ing difficulty  with  which  they  may  burrow  into  it,  and  the  ease  with 
which  their  burrows  are  maintained  when  once  dug.  Particular  animals 
prefer  soils  of  a  particular  texture,  some  preferring  rock,  some  sand,  etc. 

2.      WATER 

Most  subterranean  animals  are  submerged  in  water  during  rains. 
The  amount  of  water  which  they  encounter  in  the  soil  at  other  times  is 
determined  to  a  large  extent  by  their  relation  to  the  water  table  (57),  and 
by  the  character  of  the  soil.  The  water-holding  power  of  different  soils 
is  different.     It  increases  with  the  decrease  in  size  of  the  soil  particles  and 

157 


158  TERRESTRIAL  CONDITIONS 

with  the  addition  of  humus  which  takes  up  water  by  imbibition.  The 
amount  of  water  in  the  soil  is  usually  expressed  in  terms  of  per  cent  of 
weight,  but  a  soil  with  8  per  cent  of  moisture  may  not  give  up  water  to  an 
organism  as  readily  as  another  soil  with  only  2  per  cent.  It  is  necessary 
therefore  to  determine  the  capacity  of  a  soil  to  retain  or  give  up  moisture. 
This  has  been  determined  for  a  number  of  soils  (117,  118),  in  terms  of 
what  is  called  the  moisture  equivalent.  The  moisture  equivalent  of  a 
soil  is  the  percentage  of  water  which  it  can  retain  in  opposition  to  a  cen- 
trifugal force  1,000  times  that  of  gravity.  The  maintenance  of  turgor 
in  plants  is  believed  to  be  a  purely  physical  matter.  If  the  roots  of  a 
plant  are  in  a  mass  of  soil,  the  plant  gradually  reduces  the  water  content 
until  the  permanent  wilting  occurs.  The  willing  coefficient  of  a  soil  is 
the  moisture  content  (in  percentage  of  dry  weight)  at  the  time  when  the 
leaves  of  the  plant  growing  in  the  soils  first  undergo  a  permanent  reduc- 
tion in  moisture  content,  as  a  result  of  a  deficiency  of  moisture  supply. 
The  moisture  equivalent  of  a  soil  is  i .  84  times  the  wilting  coefficient  for 
wheat,  used  as  a  standard  plant.  Fuller  (119)  states  that  the  wilting 
coefficient  of  dune  sand  is  about  o.  75  per  cent,  while  the  usual  moisture 
content  of  the  cottonwood  dune  sand  is  two  or  three  times  this  amount. 
For  the  clay  soil  of  the  oak-hickory  forest,  according  to  McNutt  and 
Fuller  (119a),  the  coefficient  is  about  8  per  cent.  These  standards  of  soil 
moisture  indicate  the  amount  of  water  available  to  animals  through 
direct  contact  with  the  soil  or  available  for  evaporation  into  the  air  of 
cavities  which  they  construct  for  themselves  beneath  the  surface  of  the 
soil.  A  soil  gives  water  to  or  takes  water  from  the  body  of  a  subter- 
ranean animal  in  proportion  to  the  availability  of  water  in  the  soil  in 
question.     The  amount  of  available  water  increases  with  depth  (119). 

3.   TEMPERATURE 

Transeau  found  that  the  temperature  of  bog  soil  and  bog  water  is 
below  that  of  other  soils  and  waters.  This  has,  however,  not  been 
observed  for  different  dry  soils.  The  differences  between  soil  on  the 
beach  at  Sawyer,  Mich.,  August  19,  1911,  at  3:00  p.m.  and  in  the  beech 
woods  near  at  hand  was  as  follows:  Air  20°  C,  upper  half-inch  of  beach 
sand  38°-39°  C,  sandy  soil  of  beech  woods  i9°-2o°  C,  a  difiference  of 
19°  C.  The  upper  half -inch  of  bare  sand  goes  as  high  as  47°  C.  on  the 
hottest  days  of  summer,  while  the  soil  in  the  beech  woods  is  probably 
always  a  little  cooler  than  the  air  at  the  time  of  the  air  maximum. 
Dune  sand  temperature  on  the  hottest  summer  days  at  about  3 :  00  p.m. 
has  been  found  to  be  as  follows: 


ATMOSPHERE 


159 


TABLE  XXXV 

Showing  Variation  of  Sand  Temperature  with  Depth  and  Moisture  Content. 

Air  36°  C. 


1.25  cm.  below  surface 

3-4    cm.  below  surface 

8-9    cm.  below  surface 

lo-ii  cm.  below  surface 

12-13  cm.  below  surface 

17-18  cm.  below  surface 


Moist  Sand 

32°  C. 

31°  c. 
29°  c. 


27 


c. 


It  will  be  noted  from  the  table  that  temperature  decreases  with  depth 
and  with  increasing  moisture. 

4.      PLANTS   AND  ANIMALS 

Cowles  (120)  mentions  the  importance  of  soil  bacteria  which  increase 
with  the  increase  of  the  humus,  and  the  development  of  substances  toxic 
to  the  plants  producing  them  (121,  114a).  Little  is  known  of  the  effect  of 
animals  upon  the  soils  in  which  they  live  but  if  excretory  products  ever 
accumulate  in  any  quantity,  they  probably  have  a  detrimental  effect, 
especially  upon  the  animals  which  produce  them  (114).  On  the  other 
hand,  many  burrowing  animals  bury  organic  material  and  bring  mineral 
soil  to  the  surface.  The  digger  wasps  add  much  to  the  sand  by  burying 
many  insects  for  their  young.  Earthworms  contribute  to  soil  forma- 
tion (30).  Cowles  states  further  on  the  authority  of  Transeau  (122)  that 
humus  accumulation  alters  soil  aeration.  It  follows  that  the  atmosphere 
available  to  subterranean  animals  differs  in  different  soils. 


III.     Atmosphere 

Animals  living  fully  exposed  to  the  atmosphere  are  usually  those  most 
dependent  upon  the  various  physical  factors  of  the  air,  viz.,  light, 
temperature,  pressure,  humidity,  currents,  electrical  conditions,  etc. 

I.      LIGHT 

Animals  are  either  positive  or  negative  to  the  actinic  rays  of  the 
spectrum  (45,  123).  Considerable  work  has  been  done  by  plant 
ecologists,  on  the  measurement  of  light  with  photographic  papers,  but  its 
bearing  on  plant  problems  is  questioned  by  some  because  the  nonactinic 
portion  of  the  spectrum  is  most  important  in  the  process  of  photosyn- 
thesis. It  appears  that  these  measurements  are  of  much  greater  signifi- 
cance for  animals  than  for  plants.     Zon  and  Graves  (124)  have  brought 


i6o  TERRESTRIAL  CONDITIONS 

together  the  literature  and  discussed  the  methods  of  study  (see  especially 
several  papers  by  Wiesner).  The  light  in  which  animals  live  varies  from 
that  of  the  strongest  sunlight  of  mid-day  to  the  darkest  recess  of  soil,  etc. 
Many  animals  show  diurnal  migration  due  to  changes  in  light. 

2.      TEMPERATURE 

The  temperature  of  the  air  varies  with  light  (insolation).  Cloudy 
summer  days  are  about  4°  cooler  than  sunny  days.  Cloudy  winter  days 
are  warmer  (125,  p.  136)  than  sunny  ones.  The  temperature  of  the 
lowest  strata  of  air  on  sunny  days  varies  in  some  in  inverse  ratio  with  the 
distance  from  the  soil,  vegetation,  etc.  The  temperature  immediately 
above  bare  soil  may  be  very  high  in  summer  (see  Table  XXXV). 

3.  PRESSURE 

According  to  experimental  work  by  Cohnheim  and  others  (126,  127), 
man  is  sensitive  to  variations  in  atmospheric  pressure.  Many  other 
animals,  such  as  rabbits,  dogs,  etc.,  are  probably  also  sensitive.  Bird 
movements  are  often  correlated  with  variation  in  atmospheric  pressure. 
In  all  cases  the  pressure,  as  meteorologically  recorded,  represents  a 
variation  in  humidity,  etc.,  and  relations  to  pressure  alone  have  been 
but  little  studied. 

4.  HUMIDITY 

Atmospheric  humidity  (128)  is  very  important  to  animals  and 
determines  the  sensible  temperature  and  rate  of  evaporation  to  a  large 
degree  (see  under  "Evaporation,"  below). 

5.      COMPOSITION   OF   THE   ATMOSPHERE 

(Table  II,  p.  59) 
The  amount  of  carbon  dioxide  varies  (125)  in  different  localities  but 
is  usually  greatest  near  the  ground  where  decomposition  is  taking  place. 
Animals  living  among  decaying  organic  substances  probably  live  in  the 
presence  of  much  more  carbon  dioxide  than  animals  upon  vegetation. 
Carbon  dioxide  is  probably  important  to  animals  because  of  its  effect 
upon  respiratory  activity.  Carbon  dioxide  is  believed  by  some  physiolo- 
gists to  be  a  necessary  stimulus  to  the  brain  to  cause  all  respiratory 
movements.  It  is  further  held  by  some  that  mountain  sickness  (asso- 
ciated with  high  altitude)  is  due  to  decreased  carbon  dioxide  pressure. 

6.      CURRENTS 

Currents  of  wind  are  important  in  scattering  animals  and  in  affecting 
the  rate  of  evaporation  from  their  bodies.     Some  animals  take  up 


ATMOSPHERE  i6i 

definite  positions  with  reference  to  wind  (anemotaxis)  (128a),  as  for 
example  some  flies  hover  in  the  air  in  one  position  with  the  head  toward 
the  wind.  Some  animals,  such  as  the  land  salamanders,  frogs,  toads, 
millipedes,  spiders,  and  insects  turn  away  from  currents  of  air  because 
of  increased  evaporation. 

7.      ATMOSPHERIC   ELECTRICITY    (125) 

The  effect  of  atmospheric  electricity  upon  organisms  is  little  known. 
It  varies  with  variations  in  other  conditions  of  the  atmosphere.  It  will 
probably  be  found  to  be  important  in  the  life  of  animals. 


IV.     Combinations  or  Complexes  of  Factors 

As  has  already  been  pointed  out  (55),  the  animal  environment  is  a 
combination  of  moisture,  temperature,  light, pressure,  materials  for  abode 
and  food,  all  of  which  factors  taken  together  constitute  a  complex  of 
interdependences.  These  various  factors  are  so  dependent  upon  one 
another  that  any  change  in  one  usually  affects  several  others.  This 
property  of  environmental  complexes  is  what  makes  ecology  one  of  the 
most  complex  of  sciences,  and  experimentation  in  which  the  environment 
is  kept  normal  except  for  one  factor,  an  ideal  rarely  realized  in  practice, 
even  under  the  best  conditions. 

The  efforts  of  ecologists,  geographers,  and  climatologists  have  long 
been  directed  toward  the  finding  of  a  method  of  measuring  the  environ- 
ment which  shall  include  a  number  of  the  most  important  environ- 
mental factors.  De  Candolle  undertook  to  base  the  efficiency  of  a 
climate,  for  supporting  plants,  upon  the  mean  daily  temperatures  above 
6°  C,  this  temperature  being  taken  as  the  starting-point  of  plant  activity. 
Merriam  has  followed  this  lead  and  calculated  total  temperatures  for 
many  places  in  North  America  and  made  maps  and  zones  based  upon 
such  totals.  This  system,  however,  has  been  rejected  by  botanists  and 
plant  ecologists  on  account  of  much  evidence,  both  experimental  and 
observational,  which  is  quite  out  of  accord  with  this  view.  The  scheme 
has  not  been  generally  accepted  by  zoologists  outside  of  the  United  States 
Biological  Survey.  There  is  practically  no  evidence  of  an  experimental 
sort  for  the  application  of  such  a  scheme  to  animals.  Relative  humidity 
has  been  suggested  as  an  important  index  (128)  but  does  not  properly 
express  the  influence  of  atmospheric  humidity  upon  the  animal  body 
(125,  p.  53).  The  saturation  deficit  has  also  been  suggested  but  does 
not  take  temperature  into  account. 


l62  TERRESTRIAL  CONDITIONS 

I .      EVAPORATION 

''The  total  effect  of  air  temperature,  pressure,  relative  humidity, 
and  average  wind  velocity  upon  a  free  water  surface  in  the  shade  or  in 
the  sun  is  expressed  by  the  amount  of  water  evaporated"  (125,  p.  72). 
Since  temperature  in  the  season  without  frost  is  directly  due  to  the  sun's 
rays,  light  is  in  part  included.  In  our  latitude,  clouds  in  summer  slightly 
decrease  the  air  temperature  (125,  p.  72).  In  winter,  however,  the 
temperature  of  cloudy  days  is  higher.  The  strongest  light  is  usually 
associated  with  the  greatest  evaporation.  Yapp  (129)  found  that  the 
rate  of  evaporation  was  directly  correlated  with  temperature  and  illumi- 
nation, but  most  closely  correlated  with  relative  humidity.  From  the 
standpoint  of  including  many  factors,  the  evaporating  power  of  the  air  is 
by  far  the  most  inclusive  and  is  therefore  by  far  the  best  index  of  physical 
conditions  surrounding  animals  wholly  or  partly  exposed  to  the  atmos- 
phere. It  is  not,  however,  to  be  expected  that  it  will  hold  good  for  all  the 
factors  under  all  climatic  conditions,  and  for  this  reason,  records  of  light, 
temperature,  pressure,  carbon  dioxide,  etc.,  should  be  made. 

The  data  are  usually  obtained  by  using  a  porous  cup  atmometer. 
Evaporation  from  the  atmometer  is  more  nearly  like  that  from  an  organ- 
ism than  is  evaporation  from  any  other  device;  it  was  devised  by 
Livingston  (130).  "It  consists  of  a  hollow  cup  of  porous  clay  12 . 5  cm. 
high,  with  an  internal  diameter  of  2 . 5  cm.  and  a  thickness  of  wall  of  about 
3  mm.  It  is  filled  with  pure  water  and  connected  by  means  of  glass 
tubing  to  a  reservoir  usually  consisting  of  a  wide-mouthed  glass  bottle  of 
one-half  liter  capacity.  The  water,  passing  through  the  porous  walls, 
evaporates  from  the  surface,  the  loss  being  constantly  replaced  from  the 
supply  within  the  reservoir.  Readings  are  made  by  refilling  the  reservoir 
from  a  graduated  burette  to  a  certain  mark  scratched  upon  its  neck. 
For  convenience  in  handling,  a  portion  of  the  base  of  the  cup  is  coated 
with  some  impervious  substance  and,  before  being  used  in  the  field,  the 
instrument  is  standardized  by  comparing  its  loss  of  water  with  that  from 
a  free  water  surface  of  45  sq.  cm.  exposed  under  uniform  conditions.  As 
a  further  check  against  error  this  standardization  is  repeated  at  intervals 
of  six  to  eight  weeks  throughout  the  season"  (Fuller,  131).  In  Fuller's 
work,  the  bottles  were  arranged  so  that  the  evaporating  surface  of  the 
instrument  was  20-25  cm.  above  the  surface  of  the  soil, 

a)  Effect  of  evaporation  upon  animals. — In  the  case  of  man  some 
observations  have  been  made.  According  to  Pettenkoffer  and  Voit  {Ude 
125),  an  adult  man  eliminates  900  gms.  of  water  from  his  skin  and  lungs 


EVAPORATION  n 

103 


daily     Ot  this  amount  60  per  cent  or  540  gms.  come  from  the  skin  aione 
and  changes  in  relative  humidity  of  only  r  per  cent  causfperce,  title 
changes  in  the  amount  ot  evaporation  from  the  skin.     If  eZo  aion 
rom  the  skin  and  lungs  is  dmiinished,  the  amount  of  urine  isTncr       d 
as  in  many  cases  are  also  the  secretions  of  the  intestin  s     Sudde" 
changes  in   humidity  make  themselves  felt  in  sudden  ilcreas  do 
■      decreased  blood  pressure.    The  less  dilute  blood  of  dry  clLals  operate 
as  a  stimulant  and  increases  the  functions  of  the  nervously     mXh; 
consequences  are  excitement  and  sleeplessness  (1.5,  Pp.  56-5,) 

Lit  le  has  been  done  on  the  physiological  effect  of  evaporation  or 
desiccation  upon  cold-blooded  animals.     Various  writers  ha™  found  T 

ame  reTu  ::  'Z.T  " t'  '•""=™^"™-     «^'^''>'  ^'^^^  <">'--™'H 
^cime  results   with   desiccation   as   with   freezing   (t7^-    ... 

studifd' bvt  '--fl  "r'™'^  '"  "-«"  ';:^die:^s  hav^^'bre-'n 
studied  by  the  writer  (134).    A  high  rate  ot  evaporation  is  advani, 

fnrb-t"  T'  '"™^''  '"^  ^'""'"'y  detrimental'to  o  h"  tZl 
nhabiting  dense  woods  turn  back  when  they  encounter  air  with    Tigh 

millipedes.  The  frogs  and  salamanders  die  in  an  hour  or  more  n  an 
atmosphere  of  high  evaporation  power  but  centipedes  and  groZd  beetles 
and  other  heavily  armored  animals  do  not  die  for  many  hour"  or  even 

■t  in  a  gradient.  Animals  from  hot,  dry,  sand  areas  usually  select  air  of 
hgh  evaporating  power  and  die  in  air  of  high  evaporating  pwr^Llv 
after  very  long  e.x-posure.  The  results  of  a  long  series  of  ewriments 
may  be  summarized  as  follows:  (1)  the  animals  studied  react Trr  I 
a  given  high  rate  of  evaporation  whether  the  evaporltion  is  due  to 
moisture,  temperature,  or  rate  of  movement-  (.)  the  si^TZ  T 
of  reaction  to  the  given  rate  of  evaporation  are  i  I    or  Tith  the  com' 

wer::;:rd.i,rtr"'°v";''  '^^"'^'^ '™  -•''-'■  ^^^^ 

were  collected,   (3)  the  animals  of  a  given  habitat  are  in  general  asree 
ment  in  the  matter  of  sign  and  degree  of  reaction;  the  minor  dfferences' 

integument,  (4)  there  is  a  rough  agreement  between  survival  time  in  air 
of  high  evaporating  power,  and  kind  of  integument,  but  no  ag"  emen 
between  survival  time  and  habitat  when  a  number  of  members  of  aTo" 
munity  are  taken  together.     The  relation  of  warm-blooded    nt^s  To" 
a  e  of  evaporation  has  been  sufficiently  studied  so  that    whe,        i! 
taken  with  the  work  on  cold-blooded  animals,  we  are  warra'nted        on 


164 


TERRESTRIAL  CONDITIONS 


eluding  that  the  evaporating  power  of  the  air  is  probably  the  best  index 
of  environmental  conditions  of  land  animals. 

b)  Evaporation  in  different  habitats. — The  evaporating  power  of  the 
air  varies  in  different  situations  (Fig.  115).  There  are  great  differences 
between  open  prairies  and  closed  forests.  Shimek  (135)  found  that  the 
evaporation  in  the  undisturbed  groves  in  Eastern  Iowa  during  July  and 
August  was  very  much  less  than  that  in  the  prairies  adjoining.  From 
the  free  surfaces  of  pans  set  in  the  ground  so  that  the  water  which 
they  contained  was  level  with  the  surface  of  the  soil,  the  evaporation 
of  the  groves  was  about  27  per  cent  of  that  of  the  prairie;  with 
cup  evaporimeters  about  37  per  cent,  and  with  Piche  evaporimeters 


Per  cent,  of  standard "  20  40  60  80  100  120 

1.  Salt  marsh,  outer  margin... 

2.  Open  gravel  slide 

3.  Carnegie  garden,  standard .. . 

4.  Upper  beach 

5.  Salt  marsh,  inner  margin 

6.  Garden,  high  level 

7.  Gravel  slide,  partly  invaded. 

8.  Open  forest 

9.  Fresh-water  marsh 

10.  Typical  mesophytic  forest . . . 

11.  Ravine  forest 

12.  Swamp  forest 

Fig.  115. — Showing  the  comparative  evaporation  rates  in  the  ground  stratum  of 
several  animal  habitats  on  Long  Island  during  July  and  August  (after  Transeau, 
courtesy  of  the  Botanical  Gazette) . 


^ I I I I I I 


about  47  per  cent.  This  is  about  the  same  as  the  difference  on  Long 
Island  between  the  inner  side  of  Transeau 's  salt  marsh  dominated 
by  grasslike  plants  and  his  mesophytic  forest.  Sherff  (135)  found  the 
evaporation  in  a  marsh  forest  to  be  a  little  less  than  that  in  the  beech- 
maple  and  from  1.8  to  2.6  times  as  great  as  in  the  lowest  stratum  of 
marsh. 

c)  Vertical  differences  in  evaporating  power  and  other  conditions. — The 
evaporating  power  of  the  air  is  usually  greater  at  the  higher  levels  of  a 
habitat. 


STRATIFICATION 


165 


TABLE  XXXVI 

EVAPOR.^TION     FROM     PoROUS     CuP     EVAPORIMETERS     IN    DIFFERENT    STRATA     OF     A 

bUMMER  Dry  Marsh,  Cambridgeshire,  Englant),  during  Three 
Periods  between  July  9  and  September  8,  1907 
(Yapp,  129,  p.  299) 


Height  above 

Ratio  of 
Evapora- 
tion 

100.00 

32.8 

6.6 

Temperature 

Ground 

Mean 
Max. 

Mean 
Min. 

Mean 

5  ft.  6  in.  to  4  ft.  6  in. . 
2  ft.  2  in  

22.1 
23.0 
18.0 
12.7 

6.6 

7-1 
II. 2 

16. 5 

14. 1 
II. 8 

Well  above  vegetation 

A  little  above  the  mid-height 

5  in 

Soil 

Table  XXXVI  shows  marked  differences  in  the  rate  of  evaporation 
and  considerable  differences  in  temperature  at  the  different  levels  both 
due  largely  to  vegetation.  Differences  in  Hght  are  also  to  be  expected. 
Sherff  (136,  p.  420)  has  found  conditions  similar  to  the  above  by  a  two 
months'  study  of  evaporation  on  Skokie  Marsh  near  Chicago.  The 
evaporation  there  was  three  times  as  great  at  a  height  of  1.95  m.  as  at 
the  surface  of  the  soil  in  among  the  plants  of  Phragmites.  Mr.  Harvey 
has  secured  similar  (unpublished)  results  on  the  prairie  at  Chicago 
Lawn,  Chicago,  also  Mr.  Fuller,  in  the  beech  woods. 

Division  into  strata:  Plant  and  animal  habitats  are  commonly 
divided  into  strata  as  shown  below. 


Plant  (12)  after  Warming 
I.  No  such  stratum  recognized. 


4- 


Ground  stratum  made  up  of  algae, 
mosses,  immediately  above  the  sur- 
face of  the  ground. 
Field  stratum;   grasses  and  herbs. 

Shrub  stratum;  formed  of  shrubs 
taller  than  the  herbaceous  vege- 
tation. 

Tree  stratum. 


Animal 

1.  Sub-aqueous  stratum  made  up  of 
animals  requiring  water  during 
their  active  reproductive  stages. 

10.  Subterranean  stratum  made  up 
of  animals  or  stages  in  the  life 
histories  of  animals  which  inhabit 
the  ground,  especially  during  the 
breeding  season. 

2.  Ground  stratum  made  up  of  ani- 
mals or  early  stages  in  the  life  his- 
tories of  animals,  as  i. 

3-  Field  stratum;  the  inhabitants  of 
the  herbaceous  vegetation  on  land. 

4.  Shrub  stratum;  inhabitants  of 
shrubs. 

5.  Tree  stratum;  inhabitants  of  trees. 


i66  TERRESTRIAL  CONDITIONS 

V.    Quantity  or  Life  on  Land  (137) 

The  quantity  of  life  on  land  has  been  but  little  studied.  While  it  is 
evident  that  some  habitats  have  more  animals  than  others,  we  have  no 
exact  data.  As  a  rule  the  number  of  species  is  small  in  pioneer  situations. 
While  the  number  of  individuals  in  some  one  or  two  species  may  be  large, 
the  grand  total  is  probably  not  so  large  as  in  later  stages.  In  forest 
development  it  appears  from  naturalistic  observations  that  the  number 
of  both  species  and  total  number  of  individuals  increases  with  age  up 
to  the  oak-hickory  stage,  the  maximum  being  in  the  oak-hickory  stage. 
The  beech  and  maple  forest  is  qualitatively  and  quantitatively  poor  in 
animals.  Felt  (137)  records  pest  species  on  the  trees  of  the  white-oak. 
red-oak,  hickory  forest  as  follows:  Oak  in  general,  157;  red  oak,  12;  white 
oak,  31;  hickory,  30;  wild  cherry,  38;  hazel,  33;  total  401.  He  records 
pests  on  trees  of  beech  and  maple  forest  as  follows:  beech,  92;  sugar 
maple,  19;   pawpaw,  5;   total,  116. 

1.  FOOD   SUPPLY 

The  food  supply  of  land  animals  is  in  part  dependent  upon  soil.  All 
the  chief  principles  governing  the  elementary  food  substance  of  plants 
and  animals  in  water  are  given  on  pp.  65-68.  Since  all  these  processes 
are  dependent  upon  water  (as  a  solvent)  and  since  soils  at  all  times  con- 
tain some  water  (116),  the  reader  will  easily  apply  most  of  the  principles 
there  stated  to  the  soil  problem.  There  is  probably  no  kind  of  organic 
matter  found  that  is  not  food  for  some  animals.  Some  require  plants 
or  their  juices,  some  decayed  fruits,  some  wood,  some  living  animals, 
and  some  carrion.  Each  stage  of  its  decay,  a  dead  plant  or  animal  is 
food  for  some  animal. 

Certain  animals,  usually  plant-eaters,  reproduce  very  rapidly  and  are 
preyed  upon  by  many  other  animals.  Mice,  aphids,  grasshoppers  are 
examples  (26).  These  form  small  centers  about  which  many  of  the 
activities  of  a  community  rotate.  The  centers  are  indicated  by  the 
convergence  of  lines  in  Diagram  6. 

2.  EQUILIBRIUM 

The  balance  in  land  communities  is  probably  less  perfect  than  in 
aquatic  communities  even  under  strictly  primeval  conditions.  This  is 
due  to  the  fact  that  there  are  many  small  (feeding)  groups  of  organisms 
centering  around  each  of  several  rapidly  reproducing  groups  such  as 
aphids,  mice,  and  grasshoppers.  It  is  accordingly  probably  possible  for 
a  land  community  to  be  out  of  adjustment  in  some  particular  corner 


EQUILIBRIUM 


167 


without  the  maladjustment   being  felt  as  far  as  in  an  aquatic  com- 
munity of  corresponding  magnitude. 

To  illustrate  the  character  of  land  communities  in  the  matter  of  food 
supply  and  equilibrium  we  have  chosen  a  number  of  prairie  animals  and 
constructed  them  into  an  arbitrary  community.  This  community  is 
graphically  represented  in  Diagram  6.  The  arrows  point  from  the 
animal  eaten  to  the  animal  doing  the  devouring,  many  such  relations 
being  shown  on  the  basis  of  actual  published  records. 


Diagram  6. — Showing  the  food  relations  of  land  animals.  Circles  and  ellipses 
inclose  groups  of  organisms  which  are  commonly  eaten  by  the  same  animals,  and 
groups  eating  similar  food.  Arrows  point  from  the  animals  eaten  to  those  doing  the 
eating.     For  explanation  see  text. 


From  the  diagram  we  note  that  wolves  destroy  the  bison.  If  for  any 
reason  the  wolves  increased,  they  would  destroy  so  many  bison  that  the 
bison  would  decrease  because  wolves  were  abundant.  The  greater 
destruction  of  mice  in  summer  by  the  numerous  wolves  would  cause  a 
decrease  of  mice.  Finally,  wolves  would  decrease  because  of  lack  of  big 
game  in  winter  and  mice  in  summer.  This  would  give  the  bison  and 
mice  an  opportunity  to  recover  their  former  number  and  the  whole 
chain  of  changes  would  be  duplicated  and  a  general  equilibrium  be 


l68  TERRESTRIAL  CONDITIONS 

re-established.  The  decrease  of  mice  just  noted  might,  however,  cause 
the  coyote  to  eat  more  ground  squirrels  and  thus  cause  an  increase  of 
insects  because  of  the  removal  of  the  ground  squirrel  as  a  check  upon 
their  numbers.  The  numerous  checks  upon  the  numbers  of  insects 
would  tend  to  prevent  their  increasing  greatly,  but  would  no  doubt 
affect  the  greater  part  of  the  community.     The  reader  will  be  able  to 


A  B  C  D  E  F 

Diagram  7. — Representing  the  food  relations  of  the  animals  of  aland  community. 
The  circles  represent  life  histories  which  come  into  contact  or  overlap  at  the  point 
where  one  species  feeds  upon  another.  The  vertical  shafts  represent  the  animals 
which  feed  upon  the  vegetation  (herbivora  and  phytophaga).  The  extent  to  which 
the  shaft  penetrates  the  community  indicates  its  importance  as  food  of  the  forms 
whose  life  histories  are  represented.  The  letters  refer  to  the  vertical  lines  (shafts) 
above  them.  These  lines  (shafts)  represent  the  various  central  groups  of  Diagram  6 
and  other  comparable  groups  as  follows:  A,  large  herbivores  such  as  the  bison; 
B,  the  mice,  rats,  squirrels,  and  rabbits;  C,  vegetation-eating  birds;  D,  boring  insects 
secured  by  the  woodpeckers;  E,  the  large  plant-eating  insects;  F,  the  small  soft- 
bodied  insects  such  as  aphids,  scales,  etc.  The  animals  represented  by  the  shafts  are, 
figuratively  speaking,  the  propellors  which  keep  the  life  histories  shown  above  them, 
turning. 

trace  out  many  such  possible  fluctuations  and  equilibrations.  The 
number  of  possibilities  is  great  even  in  an  arbitrary  community,  though 
much  greater  in  an  actual  one. 

Diagram  7  is  a  graphic  representation  of  the  relations  of  life  his- 
tories in  land  communities  to  elementary  food  substances.  The  number 
of  plant-feeders  which  serve  to  lock  the  inorganic  substances  to  the  main 
part  of  the  community  is  far  greater  than  in  aquatic  communities. 


CHAPTER  X 

ANIMAL   COMMUNITIES   OF   THE   TENSION   LINES   BETWEEN  LAND 

AND  WATER 

I.  Introduction 

Margins  of  bodies  of  water,  swamps  and  marshes,  and  temporary 
ponds  are  on  the  border-line  between  land  and  water.  Swamps  and 
marshes  are  areas  occupied  by  plants  whose  stems,  leaves,  and  blossoms 
are  in  the  air  and  whose  roots  are  in  the  water  or  very  moist  soil, 
throughout  the  year.  Areas  covered  by  grasslike  plants  are  commonly 
called  marshes,  while  those  covered  by  trees  are  called  swamps. 
Swamps  and  marshes  usually  contain  water  the  year  round  and  are 
commonly  either  directly  connected  with  some  permanent  body  of  water 
or  are  fed  by  springs.  Others  are  dry  in  summer,  and  possess  an  active 
aquatic  fauna  only  in  spring  and  after  heavy  rains.  Our  area,  being  in 
a  region  of  glaciation,  represents  a  portion  of  one  of  the  great  marsh  areas 
of  the  world.  Geologically  speaking,  however,  these  features  represent 
the  positions  of  lakes  and  serve  to  show  us  the  fate  of  our  small  lakes 
and  ponds.  Classification  of  these  communities  is  difficult,  but  they 
may  be  divided  into  temporary  and  permanent  swamps  and  marshes 
and  into  margins  of  lakes,  ponds,  and  rivers. 

II.  Communities 

I.  permanent  water,  swamp,  and  marsh  communities 
a)  Lake-margin  marsh  sub-formation  (senescent  pond,  or  emerging 
vegetation  pond  association)  (Stations  30,  30a,  31).— About  the  margins 
of  lakes  and  ponds  there  is  often  a  girdle  of  bulrushes  and  cattails  (Fig. 
116)  which  has  a  characteristic  animal  community.  The  sub-aquatic 
stratum  is  made  up  of  pond  animals  and  has  been  considered  already  in 
chap.  viii.  There  are  a  few  characteristic  animals  which  live  chiefly 
above  the  water.  The  diving  spider  (Dolomedes  sexpundatus)  (Fig.  95) 
crawls  about  on  the  marsh  vegetation  and  dives  beneath  the  water  for 
prey.  The  long  slender  spider  (Tetragnatha  lahoriosa)  is  common  among 
the  bulrushes  (138).  At  the  base  of  the  rushes  and  sometimes  crawling 
near  the  top  is  the  snail  {Succinea  retusa)  (91).  Common  frogs  {Rana 
pipiens  and  clamata  Dan.)  (Fig.  116)  and  the  cricket-frog  {Acris  gryllus) 
hop  about  in  the  w^ater  (139). 

169 


1 70  WET  GROUND  COMMUNITIES 

There  are  also  a  number  of  insects  which  live  upon  the  vegetation 
and  never  go  into  the  water.  These  are  the  blue  and  yellow  moth 
{Scepsis  fulvicollis),  which  is  most  characteristic,  flies  which  breed  in  the 
water,  such  as  horseflies  (Tabanidae)  (140),  Tetanocera,  etc.,  also  midges, 
mosquitoes,  dragon-flies,  damsel-flies,  May-flies,  etc.  These  are  asso- 
ciated with  grasshoppers,  such  as  Stenobothrns,  Xiphidium,  and  various 


Pkrmanent  Water  jNIarsh  and  Its  Inhabitants 
Fig.  116. — General  view  of  an  open  bulrush  marsh  at  Wolf  Lake. 
Fig.  117. — Similar  but  closer  view  of  a  marsh  at  Nippersink  Lake,  showing  the 

yellow-headed   blackbird   {Xanthocephalus  xantkocephalus  Bonap.)   perched   on   the 

bulrushes.     Photo  by  T.  C.  Stephens. 

bugs  and  beetles  which  belong  to  drier  places  but  which  alight  on  the 
vegetation  above  the  water.  These  will  be  discussed  in  connection  with 
low  prairie  communities. 

The  birds  deserve  especial  attention  (108,  141).  The  pied  billed 
grebe,  the  black  tern,  and  coot  are  especially  aquatic.  The  grebe 
builds  a  nest  from  decayed  floating  rushes;  its  bottom  is  usually  wet  and 
the  eggs  commonly  lie  in  moisture.     The  black  tern  builds  a  nest  of 


SWAMP  COMMUNITIES 


171 


weeds  and  trash  similarly  situated;  the  coot  is  less  aquatic.  The  yellow- 
head  blackbird  (Fig.  117),  mallard,  pintail,  American  bittern,  the  least 
bittern  (Fig.  118),  the  Florida  gallinule  (Fig.  119),  the  long-billed  marsh 
wren,  and  sometimes  the  Virginia,  sora,  and  king  rails,  and  the  red- 
winged  blackbird  nest  in  such  situations.  These  birds  build  nests, 
either  woven  from  grasses  or  in  the  form  of  crude  piles  of  dead  vegetation, 
each  species  having  its  characteristic  method. 

The  muskrat  breeds  here  and  builds  a  nest  from  bulrushes  (Fig.  82, 


Permanent  Water  Marsh  and  Its  Inhabitants 

Fig.  1x8. — Nest  of  the  least  bittern  (Ardetla  exilis  Gmel.)  in  a  marsh  at  Nipper- 
sink  Lake.     Photo  by  T.  C.  Stephens. 

Fig.  119. — Nest  of  the  Florida  gallinule  {Gallinula  galeaia  Licht)  in  a  marsh  at 
Nippersink  Lake.     Photo  by  T.  C.  Stephens. 


p.  131).  The  mink  likewise  is  found  in  this  kind  of  situation  (22,  142, 
143).  The  grassy  outer  edges  of  such  ponds  are  the  favorite  breeding- 
places  of  frogs  {Rana  clamata)  which  stick  their  eggs  to  grass.  Points 
about  such  lakes,  especially  where  there  are  shrubs  and  willows,  are  the 
favorite  haunts  of  the  bullfrog  {Rana  catesbeiana  Shaw)  (Fig.  117). 

h)  Spring-fed  marsh  sub-formations  (Figs.  120-22)  (Stations  10,  51). — 
These  are  very  similar  to  the  marshes  which  adjoin  bodies  of  water, 


172 


WET  GROUND  COMMUNITIES 


but  the  water  of  such  marshes,  however,  gets  very  warm  in  summer, 
while  the  spring-fed  marsh  water  is  usually  cool.  It  is  the  subaquatic 
stratum  which  dififers  most. 

One  of  our  best  examples  of  spring-fed  marsh  is  at  Gary,  111.  (Fig. 
1 20).  This  contains  watercress,  which  is  usually  associated  with  springs. 
The  most  characteristic  animals  are  the  fiatworms  or  planarians.  Pla- 
naria dorotocc phala  (Fig.  121)  is  common  on  the  under  sides  of  leaves,  etc.; 


Spring  Marsh  and  Ixhaiutaxts 
Fig.  120. — A  spring  marsh  at  Cary,  III. 

Fig.  121. — Planaria  dorolocc phala;    I5  times  natural  size  (original). 
Fig.  122. — The  brook  amphipod  {Gammarus  fasciatiis);  twice  natural  size. 


if  one  puts  a  piece  of  meat  into  the  water  it  will  be  cox^red  with  worms 
within  a  short  time.  The  worms  follow  the  diffusing  meet  juices,  often 
passing  through  the  direct  sunlight,  which  they  usually  avoid.  When 
they  reach  the  piece  of  meat  they  crawl  to  the  under  side. 

Associated  with  this  planarian  is  Dendrocoelum  (144),  a  larger,  light- 
colored  species,  which  does  not  come  to  the  meat  but  is  found  with  the 
former,  under  boards,  chips,  leaves  of  plants,  etc.  The  brook  amphipod 
(Gammarus  fasciatus)  (Fig.  122)  occurs  here  also.     The  animals  of  the 


TEMPORARY  POND  COMMUNITIES  173 

vegetation  above  the  water  including  the  birds  are  about  the  same  as 
in  the  preceding  sub-formations. 

Permanent  and  temporary  swamps  are  covered  with  trees.  The 
most  important  permanent  swamps  are  the  tamarack  swamps.  The 
aquatic  phase  of  these  will  be  discussed  in  connection  with  the  tamarack 
swamp  itself  (p.  193).  Temporary  swamps  will  be  discussed  under  the 
head  of  temporary  forest  ponds. 

2.      TEMPOR.\RY   POND   OR   TEMPORARY   SWAMP  AND   MARSH 
FORMATIONS 

The  situations  known  as  temporary  ponds,  temporary  marshes  or 
swamps,  or  summer  dry  ponds,  are  common  about  Chicago  and  usually 
contain  water  in  early  spring,  drying  before  the  first  of  June.  At  some 
points  at  the  south  end  of  Lake  Michigan  much  sand  has  been  removed 
for  commercial  purposes  and  frequently  the  workmen  remove  it  to  points 
below  the  ground-water  level  of  the  spring  months  and  accordingly  make 
temporary  ponds  which  have  pure  white  sand  bottoms.  A  few  of  these 
have  been  studied,  one  when  it  was  one  year  old,  another  when  about 
twelve  years  old.  These  were  compared  with  ponds  of  the  horizontal 
series  which  are  much  older. 

a)  Bare-bottom  association.— Twelve-months  pond  association  (Sta- 
tion 40;  Table  XXXVII):  In  April,  1910,  we  found  this  pond  full  of 
filamentous  algae,  and  containing  rotifers,  copepods,  and  ostracods,  the 
eggs  of  all  of  which  will  probably  withstand  drying  and  may  have 
blown  into  the  pond  during  the  preceding  dry  seasons.  There  was  a 
single  full-grown  snail  (Physa  gyrina),  a  small  individual  (probably 
Physa  heterostropha),  and  a  small  long  snail,  Lymnaea  (probably  exigua). 
These  snails  may  have  been  carried  into  the  pond,  from  other  ponds  a 
few  rods  away,  on  the  feet  of  turtles  or  frogs. 

Twelve-year-old  pond  association  (Station  40;  Table  XXXVIl) :  As 
such  a  pond  as  we  have  just  described  grows  older,  the  algae  continue 
and  the  reed  {Juncus  balticus)  comes  in,  together  with  some  sedgelike 
plants.  In  such  ponds  the  number  of  species  is  usually  greater  than 
at  an  earlier  period. 

In  addition  to  the  species  found  in  the  twelve-months  pond,  we 
obtained  water-beetles,  which  are,  however,  not  particularly  signifi- 
cant because  they  may  occur  in  rain  pools.  Cladocera,  the  flat  snails 
{Planorbis  sp.),  and  the  nymphs  of  damsel-flies  and  dragon-flies  are 
also  found.  The  difference  between  this  pond  and  the  preceding  one 
is  not  great.     Indeed,  it  is  only  when  the  bottom  of  the  pond  becomes 


174  WET  GROUND  COMMUNITIES 

covered  with  sedges  that  we  find  marked  differences  in  the  ponds  of 
different  ages. 

b)  Vegetation  choked  temporary  pond  association  (Stations  41,  42,  43; 
Table  XXXVII)  .^Sedges  soon  take  possession  of  the  bottom  of  such  a 
pond  as  we  have  been  discussing.  Just  how  long  a  time  is  required  is  not 
known,  though  the  pond  which  we  are  about  to  discuss  is  probably 
several  hundred  years  old.  Here  we  find  nearly  all  the  groups  men- 
tioned as  occurring  in  the  younger  ponds,  but  also  certain  ecological 
types  which  are  characteristic  of  sedge-bottomed  ponds.  Most  notable 
is  the  small  green,  flat,  cigar-shaped  worm  {Vortex  viridis)  which  usually 
occurs  in  numbers,  and  a  small  brown  species  of  Mesostoma  similar 
in  form  but  brown  in  color.  With  them  are  often  small  larvae  of 
dytiscid  beetles  (species  unknown),  caddis- worms  (Phryganeidae)  with 
cases  made  from  pieces  of  grass  (their  relation  to  those  in  permanent 
ponds  is  not  known),  and  the  snail  (Lyninaea  modicella). 

As  such  a  pond  grows  older  the  sedge  becomes  thicker  and  other 
plants  make  their  appearance.  What  is  known  as  low  prairie  develops. 
At  such  a  stage  the  small  ponds  like  those  we  have  been  -describing 
usually  become  partially  filled  and  so  never  contain  the  best  development 
of  the  older  temporary  pond  community.  We  accordingly  turn  to  the 
later  history  of  the  ponds  discussed  in  the  preceding  chapters,  which 
represent  the  best  development  of  the  temporary  pond  communities. 

In  a  forest  climate  when  ponds  are  filled  and  drained  they  are 
occupied  by  forest.  In  the  steppe  climate  they  are  occupied  by  steppe 
or  prairie.  In  the  forest  border  area,  where  our  studies  have  been 
carried  on,  some  ponds  when  filled  are  occupied  by  prairies,  others  by 
forest.  Dr.  Cowles  is  of  the  opinion  that  ponds  with  gently  sloping 
sides  and  bottoms  become  covered  with  prairie,  while  those  with  steep 
slopes  become  covered  with  forest  (Fig.  123). 

As  ponds,  such  as  we  have  discussed  in  the  preceding  chapter, 
become  ecologically  old,  they  dry  in  dry  seasons.  They  usually  become 
occupied  by  cattails,  equisetum,  or  other  grasslike  plants.  The  red- 
winged  blackbird  (Fig.  124)  occasionally  nests  in  them.  At  such  a 
stage  the  isopods  (Asellus  communis  and  Mancasellus  danielsi),  amphi- 
pods  {Eucrangonyx)  (Fig.  113),  and  snails  (Lymnaea  reflexa)  (Fig.  125; 
compare  with  Fig.  104,  p.  149)  are  common.  The  fringe-legged  mosquito 
(145)  and  the  common  marsh  mosquito  (Fig.  126)  breed  in  such  situations 
while  the  crayfishes  and  various  of  the  old-pond  species  continue. 

When  such  a  stage  is  reached,  it  is  only  a  step  to  the  typical  tempo- 
rary pond.     If  the  ground- water  level  is  lowered,  as  is  the  case  in  many 


TEMPORARY  POND  COMMUNITIES 


175 


Semi-temporary  Pond  or  Marsh  and  Inhabitants 

Fig.  123. — General  view  of  Pond  93,  which  is  occupied  by  Sagiltaria  and  grass- 
like  plants. 

Fig.  124. — Side  view  of  a  red-winged  blackbird^s  nest.     Photo  by  T.  C.  Stephens. 

Fig.  124a. — The  same  from  above. 

Fig.  125. — A  temporary  pond  form  of  the  snail  {Lymiiaca  rejlexa);  natural  size. 


176 


WET  GROUND  COMMUNITIES 


of  the  ponds  south  of  Lake  Michigan,  such  ponds  usually  become  grassy 
in  the  middle  and  often  typical  temporary  prairie  ponds.  Here  we  find 
the  green  flatworm  (Vortex),  vernal  planarians  {Planaria  velata),  great 


Fig.  126. — The  common  marsh  mosquito  {Anopheles  punctipennis  Say;;  much 
enlarged  (from  Williston  after  Smith).  The  details  are  such  as  to  enable  one  to 
recognize  this  species  of  mosquito:  (i)  adult  female;  (2)  her  palpus;  (3)  her  genitalia; 
(4)  part  of  a  wing-vein  showing  scales;  (5)  anterior,  and  (6)  middle  claws  of  the  male. 


numbers  of  Entomostraca,  belonging  to  all  orders.  Of  the  last  there  are 
many  very  large  cladocerans,  the  copepods  (146)  (Cyclops  viridis 
americanus  )(Fig.  127),  the  red  copepod  (Diaptomus  stagnalis)  (Fig.  128), 


TEMPORARY  POND  COMMUNITIES 


177 


the  ostraccd  {Cyprois  marg'niata  )(i47)  (Fig.  129),  and  the  i-airy  shrimp 
(Eubranchipus)  (148)  (Fig.  130),  all  of  which  are  characteristic  of  tempo- 
rary ponds.     Red  mites  (Fig.  131)  are  also  common  (149). 

Professor  Child  (unpublished)  has  noted  that  the  distribution  each 
spring  of  Eubranchipus  and  of  other  temporary  pond  species  is  modified 


Temporary  Grassy  Pond  Animals 

Fig.  127. — A  temporary  pond  copepod  {Cyclops  viridis  amcricanus  Marsh);  35 
times  natural  size  (after  Herrick  and  Turner) . 

Fig.  128. — The  red  copepod  (Diaplonms  siagiialis)  from  temporar>'  pond;  12 
times  natural  size,  left  antenna  omitted  (after  Herrick  and  Turner). 

Fig.  129 — The  temporary  pond  ostracod  {Cyprois  marginata);  35  times  natural 
size  (after  Sharp) . 

Fig.  130. — The  fairy  shrimp  {Eiihranchipits);  3  times  natural  size. 

Fig.  131. — The  red  mite  {Hydrachna  sp.);  10  times  natural  size. 


by  the  rainfall  of  the  preceding  season.  When  the  rainfall  of  the  pre- 
ceding season  has  been  great,  the  temporary  pond  species  are  found  only 
in  the  smallest  and  highest  (above  ground-water)  ponds  such  as  would 


178  WET  GROUND  COMMUNITIES 

develop  in  the  place  of  one  of  the  small  ones  with  sandy  bottom.  Follow- 
ing dry  seasons  the  temporary  pond  species  are  found  in  ponds  which  do 
not  usually  dry  in  summer,  but  which  were  dry  the  preceding  summer. 
It  has  been  shown  that  the  eggs  of  Eubranchipus  must  be  dried  and 


Fig.  132. — The  little  smoky  mosquito  (Aedes  fusca  O.  S.);  much  enlarged  (from 
Williston  after  Smith):  (i)  adult  female;  (2)  her  palpus;  (3)  palpus  of  the  male; 
(4)  anterior;  (5)  middle,  and  (6)  posterior  claws  of  the  male. 

frozen  before  they  will  hatch.  The  relation  of  their  distribution,  follow- 
ing the  seasons  of  different  rainfall,  suggests  that  some  definite  degree 
of  drying  must  be  attained  to  insure  hatching  as  well  as  that  the  eggs 
are  probably  blown  about  by  wind.     One  autumn,  about  1900,  there  was 


TEMPORARY  POND  COMMUNITIES 


179 


early  freezing  and  cold  weather  followed  by  warm  weather  of  a  very 
springlike  character  in  December.  Professor  Child  observed  that  the 
Eubranchipus  hatched  during  this  period  of  warm  weather.  Cold  weather 
came  on  soon  after  and  most  of  those  that  had  hatched  died  before 
reaching  sexual  maturity,  and  for  several  years  after  the  species  was 
very  scarce  in  the  vicinity  of  Chicago.  Eubranchipus  is  found  only  in 
grassy  ponds,  possibly  because  the  forested  ponds  do  not  dry  sufficiently 
in  summer.     We  have  found  it  on  one  occasion  in  woods,  but  this  was 


The  Bare  Sand  Water  Margin  and  Inhabitants 
Fig.  133.— Margin  of  Lake  Michigan  at  Buffington. 

Fig.  134.— The  beach  tiger-beetle  {Cicindcla  hirticolUs);   i\  times  natural  size. 
Fig.  135.— The  beach  ground  beetle  {Bembidium  carinnla) ;  i^  times  natural  size. 

in  flood-plain  pools  following  an  early  spring  flood  and  might  have  been 
due  to  the  washing-in  of  eggs  or  young. 

c)  Forest  temporary  pond  sub-formation  (association)  (Station  50; 
Table  XXXVII).— These  are  characterized  by  the  absence  of  both 
Diaptomus  and  Eubranchipus.  The  Entomostraca  are  chiefly  ostracods, 
such  as  Cyprois  marginata,  which  occurs  in  grassy  ponds.  Vortex,  mos- 
quito larvae,  the  little  bivalve  (Musculium),  small  earthworms  (Lum- 
hriculus),  and  the  larvae  of  a  beetle  (Dascyllidae)  are  also  very  common. 


i8o 


WET  GROUND  COMMUNITIES 


The  amphipods  and  sowbugs  of  the  earlier  stages  are  still  present.  This 
is  the  breeding-place  of  such  mosquitoes  as  the  little  smoky  mosquito 
(Aedes  fuscus)  (Fig.  132,  p.  178)  (145,  99^)- 

3.      COMMUNITIES   OF   MARGINS   OF   BODIES   OF   WATER 

There  is  always  a  narrow  area  along  the  margins  of  bodies  of  water 
which  is  difficult  to  classify  as  water  or  as  land.  The  association  of 
this  area  is  the  one  with  which  we  now  have  to  deal. 

Along  the  margins  of  young  ponds  and  lakes  is  an  area  which  is 
characterized  by  being  made  up  of  wet  sand  or  mud  which  is  sub- 
merged at  high  water  and  moist  at 
other  times. 

a)  Association  of  the  terrigenous  mar- 
gins of  large  lakes  (Fig.  133)  (Stations 
57,  58;  Table  XXXVIII).— Here  we 
find  the  springtails  the  simplest  in- 
sects, the  shore  bugs  (150),  Saldidae, 
especially  Salda  humilis  Say,  a  large 
number  of  tiger-beetles  (151)  {Cicin- 
dela  hirticollis)  (Fig.  134)  (C.  cupras- 
cens),  together  with  numerous  small 
flies. 

The  ground  beetle  (Bembidium 
carinula)  (Fig.  135)  and  numerous 
scavengers  are  common  because  the 
beach  is  often  strewn  with  dead  ani- 
mals which  have  floated  ashore.  The 
relations  of  the  drift  to  other  com- 
munities will  be  discussed  in  the 
chapter  on  dry  forests.  The  spotted 
sandpiper  feeds  here,  and  with  the  piping  plover  often  breeds  not  far 
from  the  water's  edge.  Under  conditions  of  rapid  recession  of  the  lake 
such  a  margin  is  separated  from  the  wave-action.  It  is  then  rapidly 
transformed  into  the  next  association. 

b)  Association  of  the  terrigenous  margins  of  ponds  and  small  lakes 
(Stations  30,  40;  Table  XXXIX). — This  association  differs  from  that  of 
the  large  lake  in  that  the  scavengers  are  absent  and  the  animals  much 
less  active,  not  moving  about  so  rapidly.  Here  we  find  springtails, 
Saldidae  of  another  species,  and  the  toadbug  {Gelastocoris  oculatus)  (150) 
(Fig.  136),  which  is  colored  like  the  ground  and  is  found  hopping  about 


Fig.  136. — The  bare  pond  and  river- 
margin  toadbug  {Gelastocoris  oculatus) ; 
greatly  enlarged  (after  Lugger). 


WATER  MARGIN  COMMUNITIES 


l8l 


close  to  the  water.  The  tiger-beetle  of  the  Lake  Michigan  shore  is  dis- 
placed by  that  of  another  (Cicindela  repanda)  which  is  less  active.  With 
these  is  the  hooded  grou'se  locust  {Paratettix  cucullatus)  (Fig.  137)  (40, 
p.  419).  The  small  semiaqua.tic  snail  {Lymnaea  modicella)  is  frequently 
present  in  numbers. 

The  nests  of  the  spotted  sandpiper  (108,  141)  and  the  yellowlegs  are 
found  here,  and  the  birds  no  doubt  feed  upon  the  invertebrates  present 
on  the  margins  of  the  ponds  and  of  the  shallow  water. 

c)  Association  of  sedge  margins  of  ponds  and  small  lakes  (Stations 
32-34;  Tables  XL,  XLI). — As  time  goes  on,  the  sandy  margin  is 
captured  by  sedges  which  are  scattered  at  first,  so  that  the  animals  just 
discussed  continue  for  a  time  among  them  (Figs.  138,  139).  Finally, 
however,  the  ground  becomes  sodded  over 
with  sedges  and  a  low  prairie  animal  commu- 
nity comes  in,  and  the  bare  ground  animals 
disappear.  In  the  case  of  ponds  which  are 
to  develop  into  forest  this  stage  is  found 
only  along  the  young  ones.  The  sedges  are 
soon  displaced  by  shrubs  and  the  sedge 
communities  give  way  to  shrub. 

d)  Associations  of  shrub  margins  of  ponds 
and  small  lakes  (Fig.  140)  (Stations  34,  37, 
44;  Tables  XLI,  XLII).— Mr.  Allee  has 
verified  my  observations  to  the  effect  that 
the  aquatic  part  of  this  formation  is  almost 
entirely  barren ;  however,  in  summer  we  get 
the  short-winged  and  armed  grouse  locust  {Tettigidea  armata  Morse, 
and  parvipennis  Harr.)  (40)  and  the  slimy  salamander  {Plethodon 
glutinosus)  (152)  (Fig.  141).  Of  the  birds  associated  with  the  water 
we  have  here  the  wood-duck  and  the  green  heron. 

4.      MARGINS   OF   RIVERS 

(Station  29) 
Here  the  sandy  margin  is  similar  to  that  of  the  ponds  and  lake. 
Along  the  Fox  River  we  find  the  mole  cricket  (40)  which  burrows  into 
the  sand.  Mud  margins  are  rather  barren  except  for  occasional  beetles. 
The  margins  of  rivers  which  are  grassy  or  marshy  are  like  those  of  ponds 
and  lakes.  The  margins  of  the  Calumet  and  lower  Deep  rivers  are 
covered  with  marsh  plants  and  saturated  with  water  in  spring.  They 
are  the  nesting-places  of  the  long-billed  marsh  wren  (Figs.  142,  143)  and 
many  other  marsh  birds  (108,  153). 


Fig.  137. — Hooded  grouse 
locust  {Paraleltix  cucullalus) 
(after  Lugger). 


I»2 


WET  GROUND  COMMUNITIES 


139 


Fig.  138. — Prairie-like  stage  of  a  pond  margin. 
Habitat  of  Cicindela  tranqucbarica  in  the  pine 
zone  of  the  ridges  at  the  south  end  of  Lake 
Michigan.  The  dark  portion  in  the  foreground 
is  the  shadow  of  a  tree.  .\t  the  left  is  the 
cattail  zone  of  the  depression;  between  a  and 
h,  the  sedge  zone;  between  b  and  c  the  zone  of 
high-depression  plants.  The  white  blossoms 
here  are  those  of  Parnassia  caroliniana;  their 
distribution,  September,  1906,  corresponds  ap- 
proximately to  the  distribution  of  the  larvae  of 
C.  tranquebarica,  which  arose  from  eggs  laid  in 
i\Iay  and  June,  1905.  The  portion  to  the  right 
and  above  c  represents  the  higher  portion  of  the 
ridge  and  the  habitat  of  C.  scutcllaris.  Reprinted 
from  the  Journal  of  Morphology. 

Fig.  139. — The  upper  part  of  the  burrow  of 
C.  tranquebarica,  pupal  cell  shown  by  dotted 
line;  \  natural  size.  Reprinted  from  the  Journal 
of  Morphology. 


WATER  MARGIN  COMMUNITIES 

III.     General  Discussion 


183 


The  areas  which  we  have  been  discussing  in  this  chapter  are  the 
tension  lines  between  the  land  and  the  water.  It  is  in  such  areas  that 
ecologists  have  learned  most  about  succession  and  about  the  tendencies 


Fig.  140. — Pond  95,  showing  the  death  of  the  pond  by  the  growth  of  buttonbush. 

Fig.  141. — The  shiny  salamander  {Phthodon  glntinosus);    about  twice  natural 
size  (after  Fowler) . 


and  processes  in  animal  formations  and  associations.  In  this  chapter 
we  first  considered  the  marshes  which  border  the  lakes  and  ponds  about 
Chicago.  Dr.  Cowles  and  others  have  pointed  out  that  lakes  and  ponds 
are  filled  by  organic  debris  and  that  bulrushes  invade  from  the  shore  and 
"capture"  the  ponds  and  lakes.     As  the  bulrushes  and  other  plants 


1 84 


WET  GROUND  COMMUNITIES 


invade,  the  girdle  of  marsh  which  is  the  nesting  site  of  the  birds  men- 
tioned moves  farther  and  farther  toward  the  center  of  the  pond  or  lake, 
the  former  positions  being  occupied  by  shrubs,  such  as  buttonbush  or 
willow,  or  in  some  cases  by  prairie.  Such  a  situation  is  in  unstable 
equilibrium. 

Turning  to  the  margins  of  ponds,  lakes,  and  rivers,  we  note  that 
at  the  beginning  we  often  have  the  bare  sand.     This  is  first  occupied 


Fig.   142. — The  long-billed  marsh  wren's  nest.     The  nest  unopened. 
Fig.  143. — The  nest  torn  open  showing  the  eggs. 

by  reeds  and  sedges,  and  finally  by  shrubs.  It  is  this  reed  and  sedge 
group,  or  the  buttonbush,  that  invades  the  swamp  as  it  fills  with  bul- 
rushes and  cattails.  We  note  accordingly  that  the  vegetation  which 
appears  on  the  shore  invades  the  pond  as  it  fills.  The  last  stage  of 
a  pond  is  either  a  buttonbush  swamp  or  a  low  prairie  which  we  shall 
discuss  in  later  chapters. 


WET  GROUND  ANIMALS 


i8S 


TABLE  XXXVII 

Temporary  Ponds  of  Different  Ages 
The  numbers  standing  at  the  heads  of  the  columns  where  months  or  years  are 
not  indicated  refer  to  the  number  of  the  pond  in  question  when  counted  from  the  lake. 
J.P.  is  a  pond  south  of  Jackson  Park. 


Common  Name 

Scientific  Name 

Unbitferen- 

TIATED 

Prairie 

For- 
est 

12  Mo. 

12  Yr. 

4 

55 

JP. 

94 

Rotifer 

* 

* 

Copepod  

* 

Cladoceran 

* 
* 

* 
* 

* 

Ostracod 

Snail 

Physa  gyrina  Say 

Lymnaea  obnissa  cxigua 
Lea 

Snail 

* 
* 

Ground  beetle 

Bembidmm  sp 

Scavenger  beetle 

Aphodius  fimetarius 

Linn 

* 

j 

Small  water-bug 

Zaitha  fltiminea  Say. .  . 

* 

Scavenger  beetle 

Hydrophilidae 

* 

*       I 

Water-strider 

Gerridae 

* 

*       1 

Water-mite 

Hydrachna  sp 

* 

*       1 

* 

Flat  snail 

Planorbis 

* 

Dragon-fly  nymph .... 

Enallagma 

* 

* 

Toad-shaped  bug 

.  Gelastocoris  oculakis 

* 

Fabr 

* 

* 

* 

Green  flatworm 

Vortex  viridis  M.  Sch. 

Brown  flatworm 

Mesostoma  sp 

* 

* 

* 

* 

Predaceous  beetle  .... 

Dytiscidae 

* 

* 

■K 

Springtail 

Collembola 

* 
* 

* 

* 

* 
Ik 

Caddis-worm 

Neuronia .?  sp 

Pond  snail 

Lymnaea  reflexa  Say.  . 
Diaptomus  stagnalis 

* 

* 

* 

Red  copepod 

For 

* 

* 

Fairy  shrimp 

Eubranchipus  serratus 
Forbes ! 

* 

* 

Vernal  planarian 

Planaria  velaia  Str. ... 

* 

* 

Amphipod 

Eucrangonyx  gracilis 

Sm 

* 

* 
* 

* 

Isopod 

Aselliis  communis  Say. 
Culicidae i 

* 

Mosquito  larva 

* 

* 

* 

Bivalve 

Prime \ 

* 

•k 

* 

Ostracod 

Cypris  fnscata  Jurine. . ! 
Cyprois  marginata 

« 

Ostracod 

Strauss 

* 

* 

Beetle  larva 

Dascyllidae 

* 

Annelid  worm 

Lumbricidus 

inconstans  Smith 

4> 

i86 


WET  GROUND  COMMUNITIES 


TABLE  XXXVIII 

Animals  Frequenting  the  Moist  Margin  of  Lake  Michigan 
(Stations  57,  58) 


Common  Name 


Scientific  Name 


Month 


Flesh-fly 

Flesh-fly 

Flesh-fly 

Hister  beetle . 
Ground  beetle 
Tiger-beetle.  . 
Tiger-beetle.  . 


Sarcophaga  sp j  4-9 

Chrysomyia  macellaria  Fab I  4-9 

Cynomyia  cadaverina  Des j  4-9 

Saprinus  patruelis  Lee '  4-9 

Bembidium  carinula  Chd i  4-9 

Cicindela  hirticollis  Say |  6-8 

Clcindela  cuprascens  Lee ,  7-8 


TABLE  XXXIX 

Animals  Resident  on  the  Margin  of  a  Twelve- Year-Old  Artificial  Pond  antj 

OF  Wolf  Lake  (Sandy) 

(Stations  30,  40) 


Common  Name 


Scientific  Name 


Month 


Ground  beetle 

Snail 

Toad-shaped  bug .  .  .  . 

Tiger-beetle 

Hooded  grouse  locust 


Bembidium  variegakim  Say.  .  .  . 
Lymnaea  humilis  modicella  Say 

Gelastocoris  oculatus  Fabr 

Cicindela  repanda  Dej 

Faratettix  cucullatus  Burm .... 


4-9 

4-9 
4-9 
4-9 


WET  GROUND  ANIMALS 


187 


^  TABLE  XL 

Animals  Recorded  from  Sedge-covered  Pond  Margins 
(Stations  32,  33) 


Common  Name 


Snail 

Snail 

Snail 

May-fly 

Toad 

Diving  spider 

Spider 

Walking-stick 

Grasshopper  nymph .  .  . 

Damsel-bug 

Centipede 

Spider 

Long-bodied  spider .... 

Spider 

Spider 

Orb-weaving  spider .... 

Short-tongue  bee 

Ant 

Root  beetle 

Root  beetle 

Spider 

Ambush-bug 

Negro-bug 

Bug 

Red-legged  grasshopper . 

Stinkbug 

Ant 

Midge 


Scientific  Name 


Lymuaea  huniilis  modicella  Say 

Succinea  retusa  Lea 

Succinea  avara  Say 


Bnfo  hntigbiosus  Sh 

Dolomedes  sexpiinctalus  Htz 

Pirala  insular  is  Em 

Diapheromera  femorata  Say 

Acrididae 

Reduviolus  ferns  Linn 

Lithobius  sp 

Chiracanthium  iiiclusa  Htz 

Tetragnatha  laboriosa  Htz 

TibeUiis  dnttoni  Htz 

Eucia  caudata  Em 

Epeira  foliata  Koch 

Augochlora  conjusa  Rob 

Ponera  coarctala  Latr 

Diabrotica  12-punctata  Oliv 

Diabrotica  vitlala  Fab 

Dictyna  siiblata  Htz 

Phymata  fasciata  Gray 

Thyrcocoris  unicolor  P.B 

Philaronia  bilineata  Say 

Melanoplus  femnr-riibrum  DeG. .  . 

Cosmopepla  carnifex  Fab 

Formica  fusca  var.  siibsericea  Say . 
Chironomidae 


Month 


4-9 
4-9 
4-9 
4-9 
4-9 
4-9 

8-9 
6-10 
8-9 

4-9 
8-9 

8-9 
8-9 

5 
5-9 
7-8 

9 
8 


9 
3-9 


WET  GROUND  COMMUNITIES 


TABLE  XLI 

Animals  Recorded  from  the  Margin  of  Pond  8  (Mixed  Sedges  and  Shrubs) 

BY  Mr.  B.  F.  Isely 
(Station  34) 


Common  Name 


Scientific  Name 


Month 


Lygaeid 

Apple-leaf  hopper 

Lacebug  

Jassid 

Dusky  plant-bug 

Cranberry  lygaeid 

Beetle 

Ground  beetle 

Ant-like  flower-beetle 

Leaf-beetle 

Mordellid 

Case-bearer 

Strawberry  beetle 

LampjTrid 

Lampyrid 

Lampyrid 

Metallic  wood-borer 

Dascyllid 

Maia  or  buck  moth 

Short-winged  browTi  grass- 
hopper   

Slender  meadow  grasshopper . 
Short- winged  meadow  gr'hop. 

Fly 

Fly 

Fly 

Fly 

Horsefly 

Horsefly 

Syrphus  fly 


Cyvius  angustatus  Stal 

Empoasca  mali  LeB 

Physatochila  plexa  Say 

Draecidacephala  mollipes  Say .... 

Adelphocoris  rapidus  Say 

Ischnodemus  falicus  Say 

Nodonoia  tristis  Oliv 

Anomoglossus  pusilliis  Say 

Stereopalpus  mellyi  Laf 

Chalcpiis  hornii  Sm 

MordcUislena  aspersa  Mel 

Pachyhrachys  abdomiiiaUs  Say. .  .  . 
Typophorus  cancUiis  scllalus  Horn 

Lucidota  punciaia  Lee 

Pyractomena  boreal  is  Rand 

Lucidota  atra  Fab 

Pachyscclus  laevigatiis  Say 

Ptilodactyla  serricollis  Say 

Hemileuca  maiaDrxi 

Stenoholhrus  curtipeunis  Harr.  .  .  . 

Xiphidium  fasciatum  DeG 

Xiphidium  brcvipennc  Scud 

Tetanoccra  umbranim  Lin 

Tetanocera  plumosa  Loew 

Tetanoccra  combinata  Loew 

Tetanocera  saratogensis  Fitch .  .  .  . 

Chrysops  aestuans  V.W 

Chrysops  callidus  O.S 

Mesa  gramma  marginata  Say 


7-8 


7-8 
7-8 
7-8 
7-8 
7-8 
7-8 
7-8 
6-9 

7 

7 

7 

7 

7 

7 

7-8 
7-8 

7-8 
7-8 
7-8 
7-8 
7-8 
7-8 
7-8 
7-8 


TABLE  XLH 

Animals  Recorded   from   the  Willow  and  Buttonbush.    M.\rgins  of  Ponds 

52  AND  93.    Records  by  Allee  are  Indicated 

(Stations  37,  44) 


Common  Name 

Scientific  Name 

Month 

Plant-bug 

Adelphocoris  rapidus  Say  (young) 

Cosmo pcpla  carnifex  Fabr 

7-8 

Stinkbug                       

7-8 

0    Fulgorid 

Amphiscepa  hivittata  Say 

7-8 

0  Jassid 

Parabolocratus  viridis  Uhler 

Acronycta  oblinita  S  and  .\  (AUee)..  .  . 

Aphaenogaster  treatae  Forel  (Allee) 

Tetanocera  sp.  (Allee) 

Epeira  trivittata  Key.  (Allee) 

Calligrapha  muUipunctata  var.  bigsby- 
ana  Kirby  (Allee) 

8 

Smeared  dagger -moth 

Ant 

Fly 

8 
8 
8 

Spider 

8 

Leaf-beetle 

Leaf-beetle 

Typophorus  canellus  aterrimus  Oliv.  .  .  . 

CHAPTER  XI 

ANIMAL  COMMUNITIES  OF  SWAMP  AND  FLOOD-PLAIN  FORESTS 

I.    Introduction 

Swamp  forests  are  those  which  arise  in  the  areas  formerly  occupied 
by  ponds  and  lakes  and  which  grow  in  water  or  very  wet  soil.  About 
Chicago  the  many  coastal  and  morainic  lakes  of  earlier  periods  have  been 
filled  by  organic  detritus  and  more  or  less  completely  occupied  by  trees. 
Often  the  trees  have  grown  upon  floating  bogs  such  as  sometimes  occur 
about  lakes,  though  sometimes  they  have  sprung  up  on  solid  ground  and 
compact  organic  detritus. 

II.    Swamp  Forest  Formations  and  Associations 

We  shall  consider  these  forests  genetically:  the  marsh  which  often 
appears  first,  the  shrub  stage  which  follows,  and  finally  the  forest. 

I.      THE   ELM-ASH   SWAMP   FOREST   COMMUNITIES 

a)  The  marsh  association  (Station  52;  Table  XLI). — One  of  the  best 
examples  of  this  community  is  at  the  north  end  of  Wolf  Lake,  Ind.  The 
youngest  part  is  occupied  by  bulrushes  and  Hibiscus,  and  covered  in  the 
spring  by  about  a  foot  of  water  which  teems  with  small  crustaceans, 
mosquito  larvae,  and  red  water-mites.  Lymnaea  reflex,  usually  about 
half  the  size  of  the  specimens  (100)  of  permanent  ponds,  and  the  small 
bivalve  {Musculitini)  are  present.  As  the  season  advances  the  water 
dries  up  and  the  eggs  of  the  crustaceans  and  adult  mollusks  live  through 
the  dry  season  on  the  bottom  of  the  pool.  Above  the  water  on  the 
Hibiscus  are  the  small  Succinea  retusa  (91,  100),  which  belong  to  the 
forest  edge  and  low  prairie. 

b)  Shrub  association  (forest  edge  sub-formation)  (Station  52;  Table 
LXIII). — Surrounding  the  central  pool  which  we  have  described  is 
usually  a  girdle  of  buttonbush.  Here  we  recognize  several  strata.  The 
subterranean  stratum  has  few  inhabitants.      We  have  recorded  none. 

The  ground  stratum  is  not  inhabited  by  many  animals.  The  wood- 
cock and  the  northern  yellowthroat  (108,  153)  probably  occasionally 
nest  here  on  the  ground,  possibly  also  the  common  shrew  (Sorex 
personatus  St.  Hil.)  (142).     There  is  no  distinct  field  stratum,  as  the 

189 


IQO 


WET  FOREST  COMMUNITIES 


thickness  of  the  shrubs  prevents  the  growth  of  herbaceous  vegetation. 
The  shrub  stratum  is  the  chief  habitat. 

The  buttonbush  is  remarkably  free  from  plant-feeding  animals. 
Occasionally  some  of  the  willow-eaters,  such  as  the  larva  of  the  smeared 
dagger-moth,  are  found  on  it,  but  never  in  any  numbers.  This  stratum 
is  the  resting-place  of  many  of  the  insects  w'hose  early  stages  inhabit 
water.  When  the  plants  are  in  blossom,  it  is  visited  by  many  flower- 
frequenting  insects,  such  as  the  bumblebee  (40). 

Mr.  Visher  has  recorded  a  number  of  nesting  birds  in  this  girdle. 
The  wood-duck  usually  makes  its  nest  here  in  some  hollow  tree  and  lines 
it  with  feathers;  where  stumps  or  rotten  trunks  are  found  the  prothono- 
tary  warbler  sometimes  nests;  Traill's  flycatcher  {Empidonax  trailli 
Aud.)  places  its  nest  well  up  in  the  branches  and  leaves  of  the  bushes. 

c)  Forest  formation  (Stations  52  and  53;  Table  L). — As  time  goes 
on  and  the  marsh  fills  with  organic  detritus,  the  buttonbush  which  is 
continually  encroaching  upon  it  comes  to  occupy  a  position  farther  in, 
while  its  former  location  is  taken  by  the  ash,  which  is  the  next  girdle 
outside. 

The  ash  is  succeeded  by  the  American  elm  and  the  basswood.  These 
are  frequently  considerably  mixed  with  the  ash,  but  the  two  girdles  can 
be  distinguished  in  the  Wolf  Lake  Forest.  For  convenience  we  shall 
treat  these  two  girdles  (associations)  together  under  the  head  of  the  wet 
forest  formation. 

The  subaqueous  and  subterranean-ground  strata:  The  subterranean 
portion  is  inhabited  by  earthworms.  On  the  higher  parts  there  are 
doubtless  other  subterranean  forms.  Where  the  roots  of  the  grapevine 
are  in  the  drier  soil,  the  vines  are  infested  with  the  aphid  {Phylloxera) 
which  makes  galls  on  both  roots  and  leaves.  The  depressions  of  these 
forests  are  filled  with  water  in  spring  and  support  temporary  pond  ani- 
mals such  as  we  have  discussed  on  p.  179. 

In  the  Wolf  Lake  woods  we  noted  in  the  spring  of  19 10  that  the  small 
red  spiders  {Trombidium  sp.)  were  numerous.  Centipedes,  crane-fly 
larvae,  and  ground  beetles  occur  under  the  leaves.  Hancock  (40,  p.  419) 
states  that  the  obscure  and  Indiana  grouse  locusts  {Tettix  ohscura  Han. 
and  Neotettix  hancocki  Bl.)  are  found  in  such  forests.  Under  pieces  of 
rotten  wood  are  sometimes  found  specimens  of  the  small  snail  {Zonitoides 
arboreus),  which  is  first  to  appear  in  forests  developing  from  the  button- 
bush swamp  stages.  On  highest  ground  we  get  two  other  snails  (Poly- 
gyra  monodon  and  Pyramidula  striatella  Ant.)  (91,  100).  In  the  fallen 
logs  we  find  a  considerable  number  of  borers  {Parandra  brunnea  Fabr. 


SWAMP  FOREST  COMMUNITIES  191 

and  others)  and  under  the  loosened  bark  are  centipedes  (Lithobius),  miUi- 
pedes  (Polydesmus),  and  beetle  larvae  (Pyrochroidae)  which  are  flattened. 

While  we  have  no  actual  records  of  mammals  in  such  situations, 
doubtless  the  varying  hare  (Lepus  americanus  Erx.)  which  frequents 
marshy  woods  with  thickets  such  as  the  buttonbush,  the  common  shrew, 
which  nests  under  logs,  and  the  mink  {Mustela  vison  lutreocepkala'iia.rla.n) , 
all  have  been  visitors  if  not  residents  in  such  situations  in  the  past.  The 
wood-duck,  the  woodcock,  and  prothonotary  warbler  often  nest  in  such 
woods. 

Field  stratum:  The  field  stratum  is  inhabited  by  small  flies,  such 
as  crane-flies,  midges,  and  mosquitoes  {Chironomidae  and  Culicidae), 
occasional  spiders,  such  as  Theridium  frondeum,  parasitic  hymenoptera 
{Pimpla  inquisitor  Say,  Ichneumon  mendax  Cress.)  and  the  scorpion-fly 
(Panorpa),  which  breeds  in  the  ground. 

Shrub  stratum :  The  shrubs  consist  chiefly  of  buttonbushes  and  low- 
hanging  grapevines.  The  vines  frequently  have  conspicuous  insect 
galls.  One  called  the  grapevine  apple  gall,  because  of  its  shape,  is  due 
to  the  larva  of  a  small  fly  {Cecidomyia  vitis-pomum  W  and  R)  (137); 
another  which  is  a  pointed  tube  on  the  leaf  is  due  to  Cecidomyia  viticola. 
Wartlike  galls  on  the  under  side  of  the  leaves  are  due  to  Phylloxera 
vastratrix  PI.  (Fig.  277,  p.  273)  (150),  an  aphid  which,  when  introduced 
into  France,  threatened  to  destroy  the  vine  industry.  These  occur  only 
on  the  vines  on  high  ground  where  the  roots,  upon  which  a  part  of  the 
life  of  the  aphids  ia^spent,  are  out  of  water.  Several  grape  insects,  includ- 
ing the  fulgorid  bug  {Ormenis  pruinosa  Say),  have  been  taken. 

Tree  stratum:  The  tree  stratum  of  this  girdle  has  not  been  studied, 
because  the  study  of  the  tree  stratum  in  general  is  difficult.  The  white 
ash  is,  however,  attacked  by  many  insects.  Felt  (137)  and  Packard  (154) 
record  a  number.  One  of  the  most  difficult  groups  to  secure  is  the 
''borers"  of  the  solid  wood  or  sap  wood  of  trunk  and  twigs.  These  are 
chiefly  beetle  larvae,  especially  the  Cerambycidae  (155),  or  long-horned 
beetles.  The  larvae  of  these  are  legless  and  only  slightly  larger  at  the 
anterior  end.  Another  prominent  family  is  the  metallic  wood-borers  or 
Buprestidae  (155).  The  larvae  of  these  are  also  legless  and  may  be  dis- 
tinguished from  the  preceding  by  a  broad,  flattened  enlargement  just 
behind  the  head.  The  ecology  of  these  two  famflies  alone  is  a  subject 
for  a  work  the  size  of  this  volume  (see  137  and  154).  The  four-marked 
borer  (Eburia  quadrigeminata  Say)  is  said  to  occur  on  the  ash  through- 
out Indiana  (156).  The  elm  and  basswood  likewise  have  many  borers, 
some  in  common  with  the  ash. 


192  WET  FOREST  COMMUNITIES 

The  insects  feeding  on  the  leaves  are  numerous  on  all  the  trees.  The 
following  are  common  to  the  three  trees  mentioned  (137):  the  cater- 
pillars of  the  hickory  tussock-moth,  the  American  dagger-moth,  the  forest 
tent  caterpillar,  the  white-marked  tussock-moth;  each  has  a  preference 
for  one  of  the  trees.  The  larvae  of  several  other  common  moths  occur 
on  two  of  the  trees,  a  few  are  confined  to  one.  Beetle  and  sawfly  larvae 
also  attack  the  leaves.  Each  tree  has  its  characteristic  gall  insects  and 
galls;  for  example,  on  the  elm,  the  coxcomb  gall  {Colopha  ulmicola  Fitch), 
on  the  ash,  the  midrib  gall  {Cecidomyia  verrucicola  O.S.).  These  are 
believed  to  be  confined  to  particular  tree  species. 

According  to  Wood  (21)  such  forests  are  the  chief  haunts  of  the  gray 
squirrel.  The  green  heron  is  especially  likely  to  nest  on  the  low  trees 
of  such  a  forest  if  they  are  near  water. 

2.      OTHER   TYPES   OF    SWAMP   FOREST   COMMUNITIES 

The  swamp  forest  formation  is  well  developed  in  the  Skokie  marsh 
area.  We  have  visited  these  woods  at  a  point  west  of  Dempster  Street, 
Evanston.  This  was  originally  characterized  by  trees  very  much  larger 
than  those  at  Wolf  Lake,  The  soil  at  Wolf  Lake  is  sand,  while  that  at 
Evanston  is  clay,  which  is  probably  more  favorable  for  trees.  However, 
the  most  important  cause  of  the  greater  luxuriance  is  greater  age. 
The  subterranean  stratum  has  not  been  studied. 

The  ground  stratum:  Here  we  find,  in  addition  to  those  species 
of  the  temporary  ponds  at  Wolf  Lake,  a  snail  {Aplexa  hypnorum  Lmn.) 
which  is  characteristic  of  very  transient  ponds  (100). 

On  November  27,  1903,  the  condition  of  the  animals  of  this  stratum 
was  noteworthy.  In  the  lower  moister  parts  of  the  wood  we  found  the 
mollusks,  especially  Pyramidula  alternata,  in  groups  under  logs.  One  of 
these  groups  contained  12  individuals.  Under  another  log  was  a  group 
of  about  50  ground  beetles  (Platynus  sp.).  Under  one  small  piece  of 
bark  were  found  three  ground  beetles,  three  rove-beetles,  one  slug,  and 
two  snails.  Under  another,  one  tetrigid  or  grouse  locust,  several  ground 
beetles,  and  a  rove-beetle.  Under  the  bark  of  a  log  on  the  above  date 
we  found  the  hibernating  parasitic  hymenoptera  {Ichneumon  extrematatus 
Cress.,  galenus  Cress,  and  mendax),  also  a  queen  white-faced  hornet 
(Vespa  maculata),  which  with  its  colony  builds  a  large  spherical  nest 
in  a  tree  in  summer. 

Most  noticeable  of  all  was  a  group  of  several  hundred  small  blue 
chrysomelid  beetles  (Haltica  ignita  Illig.).  They  were  under  the  leaves 
at  the  base  of  a  tree  down  the  sides  of  which  individuals  of  the  same 


TAMARACK  FOREST  COMMUNITIES  193 

species  were  moving.  Such  groupings  are  common  among  hibernating 
insects  and  are  believed  to  keep  the  temperature  a  little  higher.  Baker 
(100)  has  studied  the  wet  forest  near  Shermerville,  111.  In  his  Stations 
7-1 7  the  forests  are  ecologically  older.  (For  birds  and  mollusks  present, 
see  100,  p.  468.) 

3.      THE   TAMARACK   SWAMP   COMMUNITIES 

(Stations  54,  540;  Tables  XLIII-XLV) 
Tamarack  swamps  develop  about  deep  lakes.  Floating  plant  debris 
supports  first  water-lilies  and  later  bulrushes  and  cattails.  Upon  these 
grow  shrubs,  such  as  the  leather-leaf  and  the  willows;  these  make  condi- 
tions suitable  for  the  poison  sumac  and  young  tamaracks.  The  semi- 
aquatic  plants  are  thus  succeeded  by  the  shrubs  and  finally  by  the 
tamarack. 

The  aquatic  communities  have  not  been  studied  in  a  typical  tamarack 
lake,  but  there  is  no  reason  to  suppose  that  they  differ  in  any  important 
way  from  the  aquatic  communities  of  other  old  bodies  of  water. 

a)  Floating  bog  and  forest  edge  association  (Tables  XLIII,  XLIV). — 
The  floating  bog  of  cattails  and  bulrushes  is  usually  full  of  low  places  in 
which  water  is  present  the  year  round.  Here  we  find  the  typical 
animals  of  semi- temporary  ponds,  as  described  on  p.  150.  The  various 
frogs  of  the  marsh  probably  breed  here.  Another  aquatic  habitat  of 
some  interest  is  the  water-holding  leaves  of  the  pitcher-plant  (158). 
The  pitcher-plant  mosquito  (Wyeomyia  smithii)  is  known  to  breed  in  the 
leaves  of  pitcher-plants  only.  These  are  accompanied  by  the  larvae  of 
midges  and  large  numbers  of  dead  insects  which  crawl  into  the  pitchers 
and  cannot  get  out  on  account  of  the  presence  of  many  hairs  which  pro- 
ject inward  along  the  wall  of  the  entrance. 

The  surface  of  the  bog  is  frequented  by  marsh  spiders,  insects,  and 
frogs,  only  a  few  of  which  belong  especially  to  pre-tamarack  bogs.  The 
inhabitants  of  the  vegetation  (field  stratum)  are  like  those  on  the  vege- 
tation over  other  marshes,  belonging  chiefly  to  low  prairies.  The  edge 
of  the  tamarack  woods  (Fig.  144)  is  a  characteristic  forest  margin. 
Except  for  the  presence  of  some  of  the  tamarack  leaf-feeders,  such  as 
the  larch  sawfly  larva  and  measuring-worm,  it  possesses  few  species 
different  from  the  margins  of  other  marshes  (Fig.  145). 

b)  Tamarack  forest  formation  (Table  XLV). — Pools:  The  pools 
within  the  forest  proper  contain  old-pond  animals  together  with  some 
mosquito  larvae  (such  as  those  of  Culex  canadensis)  which  are  char- 
acteristic of  pools  in  all  moist  and  mesophytic  forests  (see  99c). 


194 


WET  FOREST  COMMUNITIES 


Representatives  of  the  Tamarack  Sw.uip  Community 

Fig.  144. — View  in  the  den^e  vegetation  of  the  tamarack  swamp. 

Fig.  145. — Female  orb-weaver  {Epeira  gigas);  about  natural  size. 

Fig.  146. — ^The  brindled  locust  {Melanoplns  pundiilatus) ;  natural  size. 

Fig.  147. — An  esxmg  {Apterygida  aculeata);   natural  size. 

Fig.  148. — An  engraver  beetle  destroyer  {Cleridae,  Thanasimus  duhius);  3  times 
natural  size  (from  Blatchley  after  Wolcott). 

Fig.  149. — The  bark  of  the  tamarack,  showing  the  work  of  the  engraver  beetle 
iPolygraplms  rufipennis). 

Figs.  150,  150a. — Pickering's  tree-frog  {Hyla  pickeringii);  about  two-thirds 
natural  size  (after  Fowler) . 


TAMARACK  FOREST  COMMUNITIES  195 

Ground  stratum:  On  the  sphagnum,  which  sometimes  occurs  in  the 
pools,  various  insects  and  spiders  occur,  including,  according  to  Hancock 
(40),  two  species  of  sphagnum  crickets.  On  the  higher  ground  numbers 
of  typical  moist  forest  animals  occur  sparingly.  Frogs  are  often  numer- 
ous. The  common  frogs  {Rana  pipiens  and  clamata)  and  the  marsh 
tree-frog  {ChoropkUus  nigritus)  occur  in  summer.  The  wood-frog  and 
Pickering's  tree-frog  {Rana  sylvatica  and  Hyla  pickeringii,  Fig.  150)  are 
regular  residents;  probably  both  breed  in  the  pools  (139)  between  the 
hummocks.  Farther  north  the  hermit  thrush  nests  on  the  hummocks 
amid  the  dense  undergrowth.  This  is  also  the  typical  haunt  of  the 
varying  hare  {Lepus  americanus  Erx.)  (83,  142,  143),  which  is  white  in 
winter  and  brown  in  summer;  it  is  common  in  tamarack  swamps  farther 
north.  The  lynx  (p.  15)  was  probably  once  common  near  Chicago  and 
is  most  likely  to  have  frequented  these  swamps.  Adams  (83,  42)  records 
its  tracks  on  the  hummocks  of  the  tamarack  swamps  on  Isle  Royale  in 
Lake  Superior.  Judged  by  its  tracks  it  wanders  far.  It  feeds  largely 
on  hares,  the  numbers  of  which  fluctuate  (inversely)  with  the  numbers  of 
lynx.  The  otter  {Lutra  canadensis  Schr.)  and  Cooper's  lemming  mouse 
might  be  added  as  probable  former  residents  (143,  21). 

Field  stratum :  This  is  confined  to  hummocks  supporting  herbaceous 
plants.  Insects,  spiders  (159),  etc.,  are  common;  some  characteristic 
species  occur. 

Tree  stratum :  The  brindled  grasshopper  (Melanoplus  pundulatus) 
(Fig.  146)  has  been  found  on  the  low  branches  of  the  tamarack  and 
deposits  its  eggs  on  the  bark  of  the  trunk  or  on  stumps.  Several  other 
insects  have  been  recorded  as  common  on  the  tamarack,  among  which 
are  a  sawfly,  an  earwig  (Fig.  147),  a  lappet  moth,  and  a  woolly  aphid, 
but  we  have  not  taken  all  of  them.  (See  137,  II,  838,  and  I,  Plate  18.) 
The  tamarack  is  infested  by  bark  beetles.  In  the  swamp  at  Mineral 
Springs,  Ind.,  we  found  one  {Polygraphus  rujipennis)  (137),  sometimes 
also  Dendroctonus  simplex  Lee,  common  under  the  bark  of  partially  dead 
trees  (Fig.  149).  The  larvae  of  the  clerid  beetle  (Thanasimus  duhius) 
(Fig.  148)  (137)  occur  with  the  bark  beetles  and  feed  upon  them. 
The  adult  of  the  clerid  (137)  appears  in  spring,  having  wintered  over 
as  adult  or  in  the  late  larval  or  pupal  stage.  It  goes  about  on  the 
bark  of  trees,  seizing  the  bark  beetles  and  later  laying  eggs  at  the 
openings  of  their  galleries.  The  larvae  invade  the  galleries  and  feed 
upon  the  eggs  and  larvae  of  the  bark  beetles.  Felt  states  that  two 
other  bark  beetles  attack  the  tamarack  (160).  In  this  marsh  the  bark 
beetles  have  killed  a  number  of  trees.  In  summer  the  area  of  dead  ones 
may  be  seen  a  mile  away. 


196  WET  FOREST  COMMUNITIES 

Farther  north  the  blackburnian  warbler  nests  here.  The  tree  stratum 
of  primeval  conditions  usually  included  the  pine  marten  (Martes 
americana  Tur.).  It  lives  in  trees  in  dark  coniferous  forests.  Merriam 
(142)  says  that  it  nests  in  a  hollow  tree  or  log,  rarely  on  the  ground. 
It  preys  upon  partridges,  rabbits,  squirrels,  chipmunks,  mice,  shrews, 
birds'  eggs,  young  birds,  and  frogs  and  toads.  It  disappears  when 
civilized  man  settles  the  country.  The  marten's  close  relative,  the  fisher 
{Martes  pennanti  Erx.),  is  said  to  be  the  wildest  of  all  wild  animals.  It 
is  somewhat  similar  (21,  22,  162)  to  the  marten  in  habits. 

c)  The  pine-birch  transition  girdle  (Station  54;  Table  XL VI). — This 
succeeds  the  tamaracks  and  contains  a  few  old  trees  of  this  species.  The 
pools  are  all  dry  in  summer,  though  they  may  contain  water  in  spring. 
The  subterranean  stratum  has  not  been  investigated. 

The  ground  stratum  includes  the  frogs  of  the  tamarack  formation 
{Hyla  pickeringii).  Insects,  spiders,  centipedes,  and  snails,  which  belong 
chiefly  to  mesophytic  forest,  are  more  numerous  than  in  the  tamarack 
stage.  Nesting  of  the  ruffed  grouse  likewise  indicates  that  the  swamp 
stage  is  past.  The  field  and  shrub  strata  likewise  include  more  of  the 
mesophytic  forest  animals  than  the  true  tamarack  stage. 

The  tree  stratum  has  not  been  studied.  The  trees  are  white  pine, 
yellow  birch,  and  an  occasional  maple.  Felt  (137)  records  no  insect 
common  to  these  two  trees.  There  are  several  common  to  the  white 
pine  and  tamarack  (larch  lappet,  engraver  beetle,  etc.).  Pines  have 
many  borers  and  few  leaf-feeders.  Each  borer  usually  prefers  a  certain 
part,  as  the  trunk,  limbs,  or  growing  shoots;  some,  as  the  white-pine 
weevil  {Pissodes  strohi  Peck)  (i6i),  attack  young  pines.  Felt  records 
about  25  injurious  insects  common  to  birches  and  maples  in  general 
and  one  or  two  which  occur  only  on  yellow  birch.  The  great  crested 
flycatcher  nests  in  holes  in  dead  limbs;  the  wood  pewee  nests  on 
horizontal  limbs,  and  the  red-eyed  vireo  builds  a  nest  in  trees  from 
5  to  40  ft.  from  the  ground.  Dead  birches  form  suitable  nesting- 
places  for  woodpeckers.  The  Canada  porcupine  (142)  which  we  have 
noted  in  the  ground  stratum  is  a  good  climber  and  feeds  largely  in 
the  trees,  which  it  often  girdles. 

d)  The  geographic  relations  of  the  animals. — Most  of  the  non-aquatic 
animals  of  the  swamps  are  commonly  said  to  belong  to  species  common 
farther  north  where  conifers  dominate.  However,  our  lists  and  the 
unpublished  work  of  Messrs.  Wolcott  and  Gerhard  do  not  bear  out  this 
conclusion.  Some  of  the  species  of  these  swamps  doubtless  formerly 
occurred  among  the  hemlocks  of  Southern  Michigan. 


FLOOD-PLAIN  FOREST  COMMUNITIES  197 

e)  Fate  of  the  formation. — Most  of  our  tamarack  swamps  are  in  the 
regions  which  are  commonly  dominated  principally  by  beech  and  maple. 
In  the  higher  portions  of  the  tamarack  swamps  are  found  several  species 
characteristic  of  beech  woods  and  other  mesophytic  woods.  These  are 
the  wood-frog,  the  large  slug,  the  snail  {Polygyra  albolahris)  and  the 
red-backed  salamander  (Plethodon  cinerens)  and  the  spider  (Castianeira 
cingulata).     These  indicate  that  beech  and  maple  are  to  follow. 

4.      FLOOD-PLAIN   AND   RAVINE   FOREST   COMMUNITIES 

As  we  have  noted  on  pp.  87-93  ^^^  108-113,  streams  often  develop 
by  head-on  erosion  into  uplands  of  rock  or  clay. 

a)  Streams  developing  in  rock. — In  case  the  upland  is  of  rock,  the 
beginning  of  the  stream  is  a  lower  place  in  the  slope  of  the  rock  through 
which  water  flows  when  it  is  raining.  Vegetation  is  usually  absent.  If 
there  are  broken  pieces  of  rock  at  the  sides  or  in  the  course  of  the  inter- 
mittent stream,  some  of  the  forms  mentioned  on  p.  218  may  be  present. 
Until  it  becomes  permanent  or  has  cut  itself  a  deep,  straight-sided 
channel,  it  is  inhabited  by  the  animals  which  inhabit  the  bare  rock  of 
hills  or  hillsides.  After  the  stream  has  cut  such  a  channel,  there  are 
always  small  piles  of  fine  soils  which  support  nettles  and  other  mesophytic 
plants  similar  to  those  of  the  old  mesophytic  flood-plain.  Flood-plain 
animals  appear  early  in  the  development  of  the  stream. 

b)  Streams  developing  in  clay. — Along  the  north  shore  we  have  an 
opportunity  to  study  the  vegetation  of  ravines  of  all  ages  corresponding 
to  the  aquatic  stages  described  on  pp.  87-93.  The  slightly  lower  places  on 
the  bluff  side  in  which  water  runs  only  when  it  is  raining  are  usually  too- 
steep  to  support  plants  and  animals  as  regular  residents,  and  have  the 
same  incidental  forms  as  the  steep  bluff  (p.  210).  Later,  when  the  sides 
of  the  gully  become  less  steep,  it  is  similar  to  if  not  identical  with  the 
second  bluff  stage  (pp.  212-214);  later,  like  the  third  (p.  215),  and  still 
later,  like  the  young  forest  stage.  There  appears  to  be  little  or  no 
difference  between  the  bluff  and  the  sides  of  young  ravines.  The  outer 
ends  of  ravines  as  much  as  a  mile  and  a  half  long  are  usually  in  the  shrub 
stage  and  possess  the  shrub  community.  In  favored  situations  the  sapling 
forest,  apparently  identical  in  its  animal  associations  with  that  of  the  bluff 
(p.  215),  grows  up.  Up  the  stream,  well  back  from  the  lake,  a  distance 
of  a  fourth  of  a  mile,  conditions  become  very  different.  A  very  meso- 
phytic forest  grows  up.  In  this  we  have  possibly  some  special  features 
under  primeval  conditions,  but  in  the  ravines  along  the  north  shore 
where  the  forest  is  so  much  disturbed,  ravines  do  not  differ  particularly 


1 98  WET  FOREST  COMMUNITIES 

from  the  rest  of  the  forest,  but  animals  of  the  forest  collect  in  the 
ravines  in  dry  seasons  and  apparently  leave  the  ravines  in  the  wet 
seasons. 

We  have  noted  that  the  animal  species  living  at  the  headwaters  of  a 
stream  may  move  inland  as  the  headwaters  move  inland.  This  is  true 
of  aquatic  species.  In  the  case  before  us  none  of  the  species  of  the  young 
stream  are  at  the  headwaters  of  the  older  streams  because  the  headwaters 
of  the  older  streams  are  in  the  forest  of  the  upland  while  the  young 
streams  are  in  the  unforested  and  exposed  bluff  of  the  lake. 

c)  Flood-plain  communities. — In  streams  not  more  than  a  mile  long 
we  get  suggestions  of  a  small  flood-plain  near  the  mouth.  Here  we  find 
ragweeds  and  other  pioneer  plants  with  their  full  quota  of  animals,  such 
as  the  plant-bug  (Lygus  pratensis)  and  other  common  insects  of  rank 
pioneer  vegetation;  willows  with  their  quota  of  cecropia  caterpillars, 
viceroy  larvae,  willow-beetles,  etc.,  are  found  here  as  elsewhere.  The 
flood-plains  of  such  small  streams  are  hardly  typical  because  the  streams 
are  cutting  downward  so  rapidly.  They  doubtless  possess  many  special 
features  of  interest  which  are  subjects  for  detailed  and  special 
investigation. 

Flood-plain  forest  is  best  developed  among  such  streams  as  the 
DesPlaines  River  and  Hickory  Creek.  As  the  stream  meanders  from 
side  to  side  of  its  valley,  it  presents  points  of  deposition  and  erosion. 
The  points  of  deposition  are  best  for  the  study  of  the  development  of 
flood-plain  forest. 

Girdle  of  bare  sand  or  gravel  (Station  66) :  On  the  wet  portions  of  the 
sandy  margins  one  finds  the  ground  beetles  (Bembidium)  (156),  some- 
times toadbugs  (p.  180),  and  more  rarely  the  mole  cricket.  On  the 
higher  and  drier  portions  we  have  taken  the  Carolina  locust  {Dissosteira 
Carolina)  (40)  and  the  two-lined  locust  (Melanoplus  bivitlatus)  (40) 
hopping  over  the  ground. 

Girdle  of  ragweed  and  helianthus  (sub-formation)  (Stations  66,  71a; 
Table  XL VII) :  Here  (in  September)  we  found  several  species  of  spiders, 
the  meadow  grasshopper,  long-legged  flies,  the  leaf -hoppers,  and  the 
common  plant-bug.     This  girdle  is  later  displaced  by  willows. 

Willow  girdle  (sub-formation)  (Stations  66,  71a;  Table  XL VII): 
When  herbaceous  plants  have  grown  for  a  few  years  they  become  mixed 
with  willows  which  are  inhabited  by  animals  common  in  low  forest  mar- 
gins. Here  (in  September)  continues  the  same  meadow  grasshopper,  the 
same  plant-bug  of  the  earlier  stage.  Two  different  spiders  are  recorded 
(Pisaurina  and  Epeira).     From  willows  along  other  streams  we  have 


FLOOD-PLAIN  FOREST  COMMUNITIES  199 

taken  the  larvae  of  the  viceroy  butterfly  (163)  and  the  larvae  of  the 
cecropia  moth  {Samia  cecropia  Linn.).  Doubtless  forest-edge  birds 
nest  here  also. 

The  belt  which  succeeds  the  willow  is  commonly  found  farther  from 
the  water  and  has  not  been  so  much  studied.  It  is  commonly  made  up 
of  larger  willows,  river  maples,  young  elms,  young  ashes,  and  small 
hawthorns.  These  are  usually  much  tangled  with  weeds  such  as  nettles, 
and  masses  of  flood  trash  and  vines.  General  collecting  in  such  a  situ- 
ation along  Thorn  Creek  (August)  secured  for  us  the  large  green  stink- 
bug  {Nezara  hilaris),  the  soiny  assassin-bug  {Acholla  muUispinosa),  and 
the  broad- winged  Mgorx^ {Ampliscepsa  bivittata).  On  the  maples  are 
trequently  larvae  of  Symmerista  (Fig.  151).  On  a  small  hawthorn  were 
a  number  of  larvae  of  the  handmaid  moth  (Datana).  At  this  stage  the 
trees  and  shrubs  become  the  nesting-places  of  the  yellow  warbler  and 
American  goldfinch,  which  are  probably  our  most  characteristic  early 
flood-plain  birds. 

In  the  wet  ground  of  the  flood-plain,  especially  in  any  small  depres- 
sions made  by  overflows,  the  crayfish  (Cambarus  diogenes)  is  the  charac- 
teristic resident.  Under  driftwood  and  on  the  plants  of  the  water 
margin  is  the  slug  (Agriolimax  campestris),  and  often  also  the  snails 
(Succinea  retusa  and  avara). 

Such  situations  are  also  the  chief  haunts  of  the  beaver,  which  cuts 
away  the  saplings  to  make  its  dams.  The  otter  {Lutra  canadensis)  is 
particularly  fond  of  stream  margins.  It  feeds  upon  crayfishes,  fishes, 
frogs,  etc.  It  has  particular  powers  of  traveling  long  distances  and  i 
curious  habit  of  sliding  down  mudbanks  and  snowbanks  for  sport  (142). 
In  winter  it  progresses  on  ice  by  repeatedly  running  a  distance  and  then 
sliding  as  far  as  the  momentum  will  carry  the  body.  The  nest  is  nearly 
always  in  the  stream  bank,  with  the  entrance  below  water.  The  skunk 
the  mink,  and  the  raccoon  are  also  fond  of  the  stream-margin  thicket,  the 
latter  picking  up  fish  or  crayfish  if  they  can  be  had  at  night.  This  animal 
is  said  to  wet  its  food  before  devouring  it;  hence  the  "wachbar"  of  the 
Germans.  The  skunk  likewise  devours  almost  anything  that  is  to  be 
had  at  the  water's  edge. 

d)  Flood-plain  forest  association  (Station  68;  Table  XLVIII).— As 
times  passes  the  river  cuts  lower,  the  forest  develops,  and  we  have 
a  dense  forest  of  elm,  hawthorn,  ash,  and  basswood,  with  sometimes 
walnut  and  butternut,  these  being  partially  displaced  on  the  higher 
ground  by  the  oaks.  This  we  may  regard  as  the  t>T)ical  flood-plain 
forest. 


200 


WET  FOREST  COMMUNITIES 


Subterranean-ground  stratum:  The  nymphs  of  the  seventeen-year 
cicada  and  the  two-year  cicada  together  with  earthworms  are  always 
numerous.  The  latter  comes  out  on  the  ground  under  a  log  and  ascends 
under  the  bark  of  dead  trees  during  wet  weather. 

On  the  ground  one  finds  slugs  (Agriolimax  campestris) .  Under 
leaves,  logs,  and  bark  are  snails  {Circinaria  concava,  Polygyra  profunda, 


Representatives  of  the  Flood-Plain  Forest  Animal  Communities 

Fig.  151. — A  caterpillar  {Symmerista  albifrons)  on  the  leaf  of  the  soft  maple; 
natural  size. 

Fig.  152. — ^The  common  land  sowbug  {Porcellio  ralhkei);  twice  natural  size. 
Fig.  153. — The  scorpion  fly  {Panorpa  venosa);  much  enlarged. 
Fig.  154. — A  sphinx  caterpillar  from  Virginia  creeper;  natural  size. 
Fig.   155. — The  unicorn  larva  from  dogwood;  enlarged. 


Pyramidula  alternata,  and  Polygyra  clausa,  and  rarely  thyroides).  Land 
sowbugs  are  common  (Fig.  152).  Of  the  centipedes  we  note  the  long 
ground  form  {Geophilus  sp.)  and  sometimes  the  large  millipede  {Spiro- 


FLOOD-PLAIN  FOREST  COMMUNITIES 


20I 


bolus  marginatus).  The  white-footed  wood-mouse  (Peromyscus  leucopus 
noveboracensis  Fisch.)  nests  usually  under  a  stump  or  a  log  though  some- 
times slightly  under  ground  or  in  hollow  trees  (21).  The  short-tailed 
shrew  (Blariiia  brevicauda  Say)  and  the  common  shrew  (Sorex  personalus 
St.  Hil.)  are  common  residents. 

In  the  earher  days  (22)  the  ground  stratum  was  occupied  by  the 
larger  mammals.  The  black  bear  doubtless  found  the  delicate  herbace- 
ous plants  desirable  at  certain  times  of  the  year.  The  Virginia  deer 
occurred  here  commonly,  and  the  bison  and  elk  invaded  the  flood-plain 
forest  in  going  to  the  rivers  to  drink.  The  timber  wolf  and  the  common 
fox,  both  of  which  formerly  frequented 
all  parts  of  Illinois,  were  no  doubt  also 
to  be  found. 

Under  fallen  logs  we  find  all  the 
animals  that  are  found  on  the  forest 
floor,  and  some  others  also.  When  a 
tree  first  falls  to  the  ground,  if  it  be 
still  solid  or  living,  the  animals  which 
attack  it  are  the  same  as  those  which 
attack  it  when  it  is  standing.  If  the 
tree  be  an  oak  or  a  basswood,  one  of 
the  first  of  these  is  the  weevil  (Eupsalis 
minuta)  (Fig.  156)  (155),  which  bur- 
rows into  the  wood.  Later  the  larvae 
of  some  of  the  long-homed  beetles  are 
found  working  under  or  in  the  inner 
layers  of  the  bark.  These  are  followed  by  the  Tenebrionidae  and  the 
Buprestidae  larvae,  or  flat-headed  borers  (137).  All  these  tend  to  let 
the  water  between  the  trunk  and  bark,  which  meanwhile  has  been 
loosening  with  every  rain,  then  drying,  freezing,  and  thawing,  until  it 
soon  becomes  quite  loose.  The  space  between  bark  and  log  is  loosely 
filled  with  the  castings  of  the  many  animals  that  have  worked  over  the 
outer  wood  and  bark,  and  with  wood  and  bark  that  have  decayed  with- 
out the  aid  of  these  animals.  At  such  a  time  the  space  between  bark 
and  log  becomes  the  abode  of  the  flattened  larvae  of  Pyrochroidae, 
centipedes,  slugs,  ground  beetles,  and  nearly  all  of  the  small  animals 
mentioned  as  belonging  to  the  ground  stratum  proper.  Fallen  logs  are 
also  the  nesting-places  of  the  weasel  (Mustela  noveboracensis)  (142,  143). 

In  the  autumn  we  find  many  hibernating  animals  under  the  leaves  of 
the  floor  of  the  flood-plain  forest.     Here  we  have  found  water-striders. 


Fig.  156. — An  oak  borer  (Eupsalis 
minuta  Drury):  a,  larva;  b,  pupa; 
c,  adult  female;  d,  head  of  adult 
male;  details  of  parts  are  indicated 
(after  Riley). 


202  WET  FOREST  COMMUNITIES 

the  cutworms  from  the  field  stratum,  the  stinkbugs  and  leaf-bugs  from 
the  river  margin,  and  large  white-faced  hornets  {Vespa  maculata). 

Field  stratum:  In  early  summer  the  forms  of  the  field  stratum  are 
most  in  evidence.  There  are  scorpion-flies  (Fig.  153,  p.  200),  the  males  of 
which  have  curious  clasping  organs  at  the  posterior  end  of  the  abdomen. 
Bittacus,  the  long-legged  insect,  closely  related  to  the  former,  flies  about 
among  the  nettles;  it  has  the  curious  habit  of  seizing  flies  with  its  hinder- 
most  pair  of  legs  and  holding  them  while  they  are  being  devoured.  In 
their  breeding  both  of  these  insects  belong  to  the  ground  stratum. 

The  harvestmen,  or  daddy-longlegs,  are  always  in  evidence,  crawl- 
ing over  the  nettles  {Liohunum  dorsatuni  and  ventricosuni  being  most 
common).  Several  spiders  {Leucauge  hortorum  and  Theridiwnfrondeum) 
occur.  Numerous  bugs  including  Reduviolus  annulatus,  syrphus  flies 
(Syrphus  americanus),  and  aphids,  with  the  various  enemies  which  occur 
with  them,  are  common  here.  After  rains  we  find  many  animals  of  the 
ground  stratum  on  the  nettles  and  the  trunks  of  trees.  We  have  noted 
the  slugs  (AgrioUmax  campestris)  and  the  snails  {Polygyra  profunda  and 
thyroides)  here. 

Shrub  stratum:  The  shrub  stratum  is  well  developed.  The  dogwood 
is  one  of  the  characteristic  shrubs,  and  in  early  summer  its  leaves  usually 
are  covered  with  small  bunches  of  foam  which  upon  inspection  are  found 
to  contain  a  small  insect,  the  spittle  insec'^  {Aphrophora).  The  unicorn 
larva  (Fig.  155)  (163)  feeds  on  the  leaves  of  the  dogwood,  and  the  sphinx 
larva  on  the  Virginia  creeper  (Fig.  1S40). 

Tree  stratum:  The  tree  stratum  has  not  been  especially  studied. 
The  trees  above  the  level  of  the  shrub  stratum  are  inhabited  by  many 
borers,  lepidopterous  larvae  feeding  on  the  leaves,  and  many  birds  nesting 
in  the  branches.  The  raccoon  is  especially  fond  of  nesting  high  in  hollow 
trees  of  the  flood-plain  forest.  The  opossum,  which  was  never  abundant 
near  Chicago,  found  a  suitable  place  in  the  trees  of  the  flood-plain  with 
its  wild  grapes  and  tender  herbs.  Under  natural  conditions  this  is  one 
of  the  chief  haunts  of  the  gray  squirrel,  now  familiar  in  our  parks  (21). 
For  birds  frequenting  the  flood-plain,  see  Baker  (100,  pp.  476-78). 

The  most  striking  peculiarity  of  the  flood-plain  forest  is  its  frequent 
inundation.  In  the  spring  of  1908  we  found  the  flood-plain  of  the  north 
branch  of  the  Chicago  River  inundated  at  a  time  when  the  nettles  were 
but  a  few  inches  high.  On  the  smaU  nettles  we  found  the  common  small 
slug  {AgrioUmax  campestris)  and  the  snails  {Succinea  avara  and  retusa)  in 
great  abundance.  Caught  in  a  corner  behind  a  tree  in  some  driftwood 
we  found  a  carpenter  ant  {Camponotus),  some  flood-plain  cutworms. 


FLOOD-PLAIN  FOREST  COMMUNITIES  203 

crane-fly  larvae,  and  ground  beetles.  These  had  been  swept  into  this 
position  by  the  current.  Wood  (21)  says  that  the  white-footed  mice 
and  shrews  cHmb  the  trees  when  the  stream  is  in  flood.  As  the  number 
of  animals  does  not  seem  to  be  decreased  after  floods,  the  animals  of  the 
lower  strata  of  the  flood-plain  forest  must  be  able  to  withstand  sub- 
mergence for  days  at  a  time.  The  fact  that  these  floods  come  in  spring 
and  winter  when  the  animals  are  inactive  doubtless  assists  in  preserving 
them  because  of  the  low  ebb  of  their  metabolic  processes. 

e)  Succession  in  the  flood-plain  forest.— K^  the  stream  works  over  its 
flood-plain,  it  is  constantly  destroying  the  forest  at  some  points  and 
depositing  new  materials  upon  which  a  new  series  develops  at  other 
points.  The  depositing  sides  of  the  curves  present  the  early  forest 
stages.  Back  of  these  and  higher  above  the  stream  are  the  older  stages. 
Thus  the  horizontal  series  which  we  see  when  we  pass  from  a  depositing 
bank  across  the  various  terraces  is  a  duplication  of  the  vertical  series  at 
the  oldest  point  or  on  the  highest  terrace. 

The  higher  and  drier  parts  of  the  plain  left  by  the  lowering  of  the  river 
bed,  and  much  of  the  flood-plain  proper,  are  often  well  drained,  rarely 
flooded,  and  when  thus  drained  pass  rapidly  into  the  oak-hickory  type. 
At  such  a  stage  the  oak-hickory  animal  association  is  present  and  the 
characteristic  flood-plain  animals  have  disappeared. 

/)  Comparisott  with  other  moist  forests— There  are  a  few  species 
common  to  the  marsh  and  flood-plain  forests.  This  is  true  of  several 
mammals  and  insects.  One  of  the  most  characteristic  of  the  insects  is 
the  scorpion-fly.  Many  of  the  others  belong  particularly  to  the  trees 
common  to  the  two,  such  as  the  ash,  elm,  basswood,  etc. 


204 


WET  FOREST  COMMUNITIES 


TABLE  XLIII 

Animals  from  the  Open  Pre-Tamarack  Bog  Dominated  by  Bulrushes, 
Sedges,  and  Similar  Plants 

Animals  recorded  from  Tamarack  Swamps;  M  from  the  swamp  at  Mineral 
Springs,  Ind.  (Station  54),  and  P  from  that  near  Pistakee  Lake,  111.  (Station  54a). 
Numbers  refer  to  month  in  which  the  specimens  were  taken,  f  indicates  that  the 
species  has  been  taken  from  low  prairie;  *  that  it  has  been  taken  from  high. 


Common  Name 

Scientific  Name 

Habitat 

Marsh  and 
Month 

Midge  larva 

Mosquito  larva 

Caterpillar 

Ground  beetle  (dead) 
*Orb-weaving  spider 
(dead) 

Chiroiiomus  sp 

Wyeomyia  smilhii  Cq 

Nocluinae  larva 

Amara  polita  Lee 

Rpcira  foliala  Koch 

Pitcher-plant 

u 
u 

a 
Pool 

u 
a 
u 

Surface  ground 

u 
u 

Vegetation 

II 

II 
II 
II 
II 
II 

(I 
u 
II 

II 
II 
u 
u 
u 
a 
u 
u 
II 

(1 

Ms 
Ms 
M  s 
Ms 

M  5 

*  Jumping  spider 

(dead)  

Snout-beetle  (dead) .  . 

Ant  (dead) 

Water-beetle 

Phidippus  podagrosus  Htz 

Listrouotus  caUosus  Lee 

DoUchodcrus  marine  Forcl 

Helophorus  lineatus  Say 

Planorhis  parvus  Say 

Cambarus  diogcncs  Gir 

Ms 
Ms 
Ms 
P   8 

Flat  snail 

Crayfish       

P   8 
M  , 

Entomoslracd 

Snail 

Succiiica  rcliisa  Lea 

Circinaria  concava  Say 

Pisaurina  uiidata  Htz 

Pirata  montana  Em 

Sistrurus  calcnaiHS  Raf 

Plalyiiiis  picipennis  Kirby 

Liobunum  graiide  Say 

Epeira  prompta  Htz 

Pledana  slcUala  Htz 

Ms 
Ms 
Ms 
Ms 
Ms 
M  5 
Ms 
Ms 
M  s 

Snail 

fSpider  {Pisauridac)  . 

Running  spider 

fMarsh  rattlesnake .  . 

Ground  beetle 

Harvestman 

*Orb-weaving  spider. . 
t*Orb-weaving  spider. 

fGarden  spider 

Argiope  Irifasciala  For 

P   8 

fDictynid 

Diclviia  siiblala  Htz 

*Crab  spider 

jCrab  spider 

Runciiiia  aleatoria  Htz 

TibeUiis  diitloni  Htz 

P   8 
P    8 

Jumping  spider 

Jumping  spider 

t  Orb-weaving  spider . 
Meadow  grasshopper . 

Hoosier  locust 

t*Grasshopper  {Acrl- 
didae)          

Dendryphanlcs  oclavus  Htz 

Thiodina  puerpera  Htz 

Eugnatha  stramiiiea  Em 

OrcheUmuni  glaberrimum  Burm .  . 
Paroxya  lioosieri  Bl 

Slenobolhrus  curt i ponds  Harr 

Pelogonus  americanus  Uhl 

"^  Lepyronia  quadrangularis  Say .  .  . 
Pentagramma  viitatijrons  Uhler.  . 

P   8 
Ms 
Ms 
P   8 
P   8 

P   8 

f  Toad-bug 

M5 
P   8 
P   8 
P   8 

Bug  (Cercopidae) 

Bug  (fulgorid) 

Braconid 

Ant 

Formica  fusca  Lin 

P   8 

Fly  (Sciomyzidae). .  .  . 

Sepedon  pusillus  Loew 

Ms 

Ms 
Ms 
Ms 
Ms 

Snout-beetle 

Boris  confinis  Lee 

Snout-beetle 

*Lampyrid  beetle.  .  .  . 

Brachybamus  elechis  Germ 

Telephorus  lineola  Fab 

Snout-beetle 

Listronolus  inaequalipennis  Boh . 

WET  FOREST  ANIMALS 


205 


«  TABLE  XLIV 

Animals  Recorded  from  Margin  of  Tamarack  Forest— Forest  Edge 
Abbreviations  as  in  Table  XLIII 


Common  Name 

Spider 

Snail 

Slug 

Camel  cricket 

Millipede 

Firefly  larva 

Tortoise  beetle 

Ground  beetle 

Tree-frog 

Crab  spider 

Stinkbug 

Jumping  spider 

Orb- weaving  spider. . 
Orb-weaving  spider. . 

Katydid 

Ant 

Pickering's  frog  .... 

Beetle 

Earwig . 


Scientific  Name 


A  rgiope  trifasciata  For 

Vitrea  indcnlala  Say 

Agriolimax  campestris  Binn. 

Ceuthophilus  sp 

Polydesmus  sp 

Lampyridae  sp 

Coptocycla  bicolor  Fab 

Pterostichus  lucublandus  Say . 

Hyla  versicolor  Lee 

Philodromus  oniatiis  Bks.  .  .  . 
Euschistus  Iristigmus  Say .  .  .  , 
Dcndryphantcs  mUitaris  Htz. , 

Epeira  trifoliitm  Htz 

Epeira  triviUata  Key 

Amblycorypha  sp 

Formica  fusca  Linn 

Hyla  picker ingii  Hoi 

Laiigiiria  gracilis  Newm 

\ptcrygida  acideata  Scud. 


Brindled  locust j  Mclaiwplus  punclulatus  Scud. . 


Orb- weaving  spider 

Jumping  spider 

Sawfly  larva 

Caterpillar 

Fly 

Spider 

Long-bodied  spider. . 

Harvestman 

Jumping  spider 

Red  mite 

Ground  beetle 


Habitat 


Locality 
and  Month 


Ground 


Epeira  gigas  Lea . 
Dendryphantes  militaris  Htz. .  .  . 

Nemalinac 

Geometridae 

Mesogramma  marginata  Say  . .  . 
Chiraainl/iiitm  inclusa  Htz  .... 

Tetragnatha  grallator  Htz 

Liobunum  dorsatum  Say 

Dendryphantes  octavus  Htz 

Trombidium  sericeum  Say 

Platyniis  decens  Say , 


Shrubs 


Young  tamarack 


P 
M 
M 
M 
M 
M 
M 
M 
M 
M 
]M 
Mg 
P   8 
P   8 
P   8 
Ms 
M9 
M  5 
]Vl9 
M9 
M9 
M  9 
P   8 
P   8 
M5 
P   8 
P   8 
P   8 
P   8 
Ms 
Ms 


P8 


2o6 


WET  FOREST  COMMUNITIES 


TABLE  XLV 

Tamarack  Forest 
For  meaning  of  abbreviations  see  Table  XLIII 


Common  Name 


Mosquito 

Amphipod 

Sowbug 

Copepod 

Copepod 

Copepod 

Copepod 

Spider  (lycosid). 

Spider 

Millipede 


Millipede. 


Snail 

Slug 

Snail 

Crane-fly  larva .  . 
Ground  beetle . .  . 
Swamp  tree-frog . 

Wood-frog 

Snail 


Ground  beetle . 
Ground  beetle . 


Engraver  beetle 

Engraver  destroyer 

(larva) 

Borer  (larva) 

Spider 

Spider 

.      Spider 

\/0  Leaf -hopper 

Leaf-bug 

()  Tree-hopper 

Caterpillar 

Beetle  {Melandryidae) 

Tortoise  beetle 

Jumping  spider 

Orb-weaving  spider. .  . 
Orb-weaving  spider. . . 

Long  spider 

Jumping  spider 

Jumping  spider 

Die  tynid  spider 

O  Leaf -hopper 

a  Bug 

Leaf -bug 

/  C  Leaf -hopper 

Spider 


Scientific  Name 


Culcx  canadensis  Theob 

Eiicrangonyx  gracilis  Sm 

Asellus  communis  Say 

Canthocamptus  norlhumhricus  Br, 
Cyclops  viridis  atnericanus  Mar .  . 

Cyclops  serrulalus  Fisch 

Cyclops  albidus  Jurine 

Pirata  piratica  CI 

Mangora  maculata  Key 

Scytonoius  gramdatus  Say 


Polydesmus  sp . 


Zonitoides  arborciis  Say 

Philomycus  carolinensis  Bosc. 

Circinaria  concava  Say 

Tipulidae 

Plerostichus  coracinus  Newm . 

Chorophilus  nigriius  Lee 

Rana  sylvatica  Lee 

Polygyra  muUilineata  var. 

algonquinensis  Nason 

Plerostichus  adoxus  Say 


Habitat 


Pools 


Sphagnum 

u 

Under  log  and 

bark 
Under  log  and 

bark 
Under  log 


Pkroslichus  pennsylvanicus  Lee 
Polygraphus  rufipennis  Kirby .  . 


Thanasimus  diihius  Fab 

Cerambycidae 

Epeira  ocellata  CI 

Habrocestiim  pulex  Htz 

Theridium  frondctim  Htz.  .  .  . 

Gypona  striata  Burm 

Poccilocapsus  linealus  Fab.?. 
Cercsa  borealis  Fair 


Synchroa  punctata  Newm 

Coptocycla  clavata  Fabr 

Zygoballus  bettini  Peck 

Epeira  gigas  Lea 

Epeira  foliata  Koeh 

Telragnatiia  grallator  Htz 

Dendryphantes  octavus  Htz 

Dendryphantes  militaris  Htz .  .  . 

Dictyna  foliacea  Htz 

Cicadula  var  lata  Fall 

Scaphoideus  immistus  Say 

Lygus  plagiatus  Uhler 

Gypona  octolineata  Say 

Pisaiirina  nndata  Htz 


Under  log 


Ground  under 

bark 
Ground  under 

bark 
Ground  under 

bark 
Early  decay 


Decaying  wood 

u 

Under  loose  bark 
Herbs 


Undergrowth 


Locality 
and  Month 


Ms  P 

M  59 

M  59 

M69 

M9 

M9 

M9 

M9 

M9 

M9 

M9 

M95 
M9 

M9S 
M9 
M9 
M9 

M  59 
P  8 

M5 

M9 

M  59 

M  59 
M59P 
P  8 
P  8 
P  8 
P  8 
P  8 
P  8 
P  8 
P  8 
P  8 
M9 
Ms9 
M9 
M9 
M5 
M5 
M5 
M9 
M9 


WET  FOREST  ANIMALS 
0  TABLE  XLV—Coiilinued 


207 


Common  Name 

Scientific  Name 

Habitat 

Locality 
and  Month 

Beetle  (Dermestidae) . . 

Cryptorhopalu  m  ha  emorrholda  le 
Lee 

Undergrowth 

u 
a 
u 
u 
u 
u 

Low  shrubs 

u 

Mq 
Ms 
Ms 

Ms 
M  c 

Beetle  {Scarabaeidae) 

Chakpus  nervosa  Panz 

Lady-beetle 

Psyllobora  20-maculata  Say 

Cyphon  variabilis  Thunb 

CyphoH  padi  Linn 

Beetle  (Dascyllidac) .  . 
Beetle  (Dascyllidae) .  . 

Beetle  {M elandryidac) 

Allopoda  lutea  Hald 

iVJ.   5 

Ms 
Ms 
Ms 

AT   r 

Pummice-fly 

Ant 

Drosophila  amoena  Locw 

Formica  fusca  Linn 

Dictynid  spider 

Dictyna  sublata  Htz 

Spider 

Hypselistes  florens  Cam 

CU       U                          -\t  "^ 

iVl  5 

TABLE  XLVI 

Animals  of  the  Birch-Maple  Belt,  Which  Succeeds  the  Tamarack  at 

Mineral  Springs 

(Station  54) 


Common  Name 


Red  mite 

Snail 

Ground  beetle. . . . 
Melandryid  beetle 

Rove  beetle 

Clubionid  spider .  . 

Horn  tail 

Wood-frog 

Salamander 

Salamander 

Spider 

Tree-frog 

Spider 

Spider 

Spider 

Beetle 

Beetle 

Ant 

Leaf-beetle 


Scientific  Name 


Trombidium  sericeum  Say 

Polygyra  albolabris  Say 

Pterostickus  adoxiis  Say 

Phloeotrya  quadrimaculala  Say. . 
Listotrophus  cingidatus  Grav.  .  . 
Castianeira  cingidata  Koch  .... 

Xiphydria  maculata  Say 

Rana  sylvatica  Lee 

Plethodon  cinereus  Gr 

Plethodon  glutinosus  Gr 

Agelena  naevia  Wal 

Hyla  picker ingii  Hoi 

Phidippus  audax  Htz 

Dendryphantes  tnilitaris  Htz ... 

Misumessus  oblongus  Keys 

Cyphon  padi  Linn 

Photinus  corruscus  Linn , 

Camponotus  heradeanus  ligniper 

dtis  var.  noveboracensis  Fiteh. 
Calligrapha  muUipiinctata  var. 

bigsbyana  Kirby 


2o8 


WET  FOREST  COMMUNITIES 


TABLE  XLVII 

Animals  Occurring  in  the  Ragweed  and  Willow  Thicket  Stages  of  Flood- 
Plain  Forest  Development 
(Stations  66,  67,  71a) 
Ragweed  Stage 


y 


Common  Name 

Scientific  Name 

Habitat                 Month 

Snail 

Succinea  avara  Say 

Succinea  retusa  Lea 

'.'.'.'.'.'.'.                 8- 

'.'.'.'.'.'.'.                 8- 

8- 

8- 

Meadow  grasshopper. 
Tarnished  plant-bug. . 
Spider 

Xiphidium  brevipenne  Scud 

Lygiis  pratensis  Linn 

Argiope  trifasciala.  For 

■9 

-9 

Long-bodied  spider. .  . 
Meadow  grasshopper . 

Tetragnatha  laboriosa  Htz 

Orchditmiyn  glaberrimum  Burm .  . 

-9 
-9 

TmcKET  Stage 

The  Succineas  above  continue 

Succinea  ovalis  Say 

Plants 
WiUow 

u 

Grape 
Weeds  and  willow 

Haw            1       . 

WiUow 

Willow                 '. 

u 
u 
u 

Katydid 

'       Grape  scarabaeid .... 

'^   Fulgorid  bug 

0  Cercopid  bug 

Assassin-bug 

Stinkbug 

Spider 

Spider 

0  Bythoscopid  bug 

Sawfly  larva 

Leaf-beetle 

Amblycorypha  oblongifolia  DeG.  . 
Pelidnota  punctata  Lin 

Amphisccpa  bivittata  Say 

Lepyronia  quadrangular  is  Say.  .  . 

Acholla  multispinosa  DeG 

Nezara  hilar  is  Say 

Pisaurina  undata  Htz 

Epeira  gigas  Lea 

Idiocerus  snowi  G.  and  B 

Citnbex  americana  Lea 

Crepidodera  helexinus  Lin 

TABLE  XLVIII 

Animals  Usually  Common  on  Herbaceous  Vegetation  (Chiefly  Nettles)  of 
THE  Riverside  Flood-Plain  Forest  (Oak-Elm  Stage)  in  June  and  July 
Those  starred  occiir  in  the  corresponding  stages  of  marsh  forests. 


Common  Name 

Scientific  Name 

*Dictynid  spider     

Dictyna  foliacea  Htz. 
Theridium  frondeum  Htz. 

*Spider        

Spider  {Epeiridae) 

Leucauge  hortorinn  Htz. 

*Harvestman 

Liobunum  dorsatum  Say 

*Harvestman 

Liobmium  ventricosum  Wood 

False  crane-fly 

Bittacus  strigosus  Hag. 

*Scorpion-fly   

Panorpa  venosa  Westw. 

*SnaU 

Polygyra  thyroides  Say  (moist  days) 

Lampyrid  beetle       

Podabrus  rugulosus  Lee. 

Long-horned  beetle 

Slrangalia  acuminata  Oliv. 

Click-beetle 

Limoniiis  interstitialis  Melsh. 

Scarabaeid  beetle 

Chalepus  scapularis  Oliv. 

Snout-beetle 

Rhinoncus  pyrrhopus  Lee. 

Damsel-bug 

Reduviolus  annulatus  Reut. 

Capsid  bug 

Plagiognathus  fuscosus  Prov. 

Fly  {Psilidae) 

Loxocera  pectoralis  Loew. 

PROPERTY  OF 

Z,  p.  METCALF 


CHAPTER  XII 

ANIMAL  COMMUNITIES  OF  DRY  AND  MESOPHYTIC  FORESTS 

I.    Introduction 

The  forest  communities  discussed  in  the  preceding  chapters  are  those 
displacing  aquatic  communities.  In  a  climate  suitable  for  forests,  trees 
spring  up  on  high,  well-drained  surface  materials  of  all  kinds.  Forest 
appears  on  rock,  sand,  clay,  etc.,  first  as  shrubs  or  scattered  trees,  later 
as  dense  mesophytic  forest.  In  the  region  about  Chicago  we  have  forest 
in  all  stages  of  development  and  on  several  kinds  of  material. 

The  bluffs  of  the  lake  and  artificial  exposures  of  clay  along  the  drain- 
age canal  and  the  till  uplands  afford  examples  of  development  peculiar 
to  this  t>^e  of  soil.  The  few  outcrops  of  Niagara  limestone  and  the 
quarries  and  rock  dumps  present  scattered  data  on  the  history  of  forests 
on  rock.  The  extensive  sand  areas  afford  examples  of  all  stages  of 
development  peculiar  to  sand.  From  all  these  situations,  we  find 
forests  leading  toward  some  type  related  to  climate,  either  the  topical 
forest  of  the  forest  climate,  or  the  forest  of  the  savanna  climate. 

II.  Forest  Communities  on  Clay 
(Fig.  157)  (55) 
The  chief  areas  of  more  or  less  active  erosion  are  along  the  west  side 
of  the  lake,  from  Waukegan  to  Winnetka,  and  on  the  east  side  of  the 
lake  from  South  Haven  to  Benton  Harbor.  The  old  bluffs  of  the  Tolles- 
ton  and  Calumet  stages  as  represented  north  of  Waukegan  and  at 
various  other  points  offer  valuable  areas  for  comparison.  There  are 
also  similar  bluffs  along  many  of  our  streams,  some  of  those  in  Michigan 
being  very  old. 

When  the  ice  sheet  receded  entirely  and  left  the  outline  of  Lake 
Michigan  much  as  it  is  now,  doubtless  the  shore  presented  a  more  or  less 
rounded  profile.  However,  since  that  time  waves  have  gradually 
changed  the  shore  profile.  By  washing  away  the  clay  at  the  base  of 
such  a  shore,  a  bluff  has  been  developed  (62). 

I.     steep  bluff  association 
(Station  56;  Table  XLIX) 
a)  Ground  stratum  (55)  (Fig.  157). — In  spring,  when  the  frost  goes  out 
of  the  ground,  leaving  the  clay  somewhat  loosened,   the  ground-water 

209 


2IO 


DRY  AND  MESOPHYTIC  FOREST  COMMUNITIES 


level  is  high,  and  gravitation  overcomes  the  viscosity  of  the  clay,  and 
great  masses,  whose  consistency  is  that  of  thick  mud,  slump  down  in  the 
form  of  landslides.  This  process  naturally  decreases  the  angle  of  slope  at 
the  points  where  the  slumping  takes  place.  Slumping  does  not  occur 
equally  everywhere  and  the  bank  becomes  very  irregular.  Under  such 
conditions  the  only  animals  present  are  the  Collembola.  In  summer  the 
steep  bank  dries.  No  animals  are  present  as  actual  residents.  The 
bank  serves  only  as  a  casual  alighting-place  for  tiger-beetles,  butterflies, 
bees,  flies,  and  other  insects.     Few  or  no  plants  are  present. 


157 


Fig.  157. — Upper  figure  is  a 
diagram  showing  Lake  Michigan 
bluff  as  seen  from  the  zenith. 
U,  level  surface  of  upland;  BL, 
bluff;  SB,  sandy  beach;  M, 
water  of  Lake  Michigan;  /, 
piers;  toward  the  left  is  north; 
sand  has  lodged  on  the  north  side 
of  the  piers.  AB  and  CD  indi- 
cate positions  of  cross-sections 
below.  Middle  figure  is  a  cross- 
section  AB.  Slumping  bluff 
stage.  The  adults  of  Cichidela 
limbalis  are  distributed  from  A 
to  B;  the  larvae,  sparingly,  from 
E  to  F.  Other  letters  as  in  the 
upper  figure.  Lower  figure  is  a 
cross-section  CD;  stage  of  some 
bluff  stability  and  bare  clay 
exposure.  Adults  of  limbalis 
between  C  and  D;  larvae  plenti- 
ful between  G  and  //.  Other 
letters  as  above.  Reprinted 
from  the  Journal  of  Morphology. 


Unless  something  interferes  with  the  action  of  the  waves  the  same 
series  of  events  just  described  continues  from  year  to  year.  If  for  some 
reason  the  action  of  the  waves  is  checked,  the  associated  processes  will 
be  checked  also.  At  various  points  along  the  shore  piers  have  been  built 
out  into  the  water  at  right  angles  to  the  shore  for  a  distance  of  a  hundred 
meters  or  more  (Fig.  157).  The  currents  in  the  lake  are  southerly  in 
direction  along  the  west  shore.  Whenever  water  in  motion,  laden 
with  material  picked  up  by  its  action  against  the  bluff,  strikes  one  of 
these  piers,  its  velocity  is  decreased  and  a  part  of  the  material  is  dropped 


ON  CLAY 


211 


on  the  north  side  of  the  jetty.  Materials  thus  deposited  gradually 
pile  up  to  such  an  extent  as  to  protect  the  base  of  the  cliff  from 
wave-action.  Thus  the  effect  of  the  slumping  of  the  springtime 
(tvhich  tends  to  reduce  the  angle  of  slope)  is  not  fully  removed  from 
year  to  year. 

d 


Fig.  1 58. — The  bluff  habitats  near  Glencoe,  111.,  showing  several  stages  in  the 
development  of  the  forest  on  the  bluff.  The  area  to  the  right  of  a  line  between  a  and  b 
is  stable  enough  to  support  some  sweet  clover.  Here  the  tiger-beetle  larvae,  spider, 
etc.,  are  most  abundant.  The  area  between  lines  joining  a  and  b  and  a  and  c  is  in  the 
early  shrub  stage.  To  the  left  of  ac  the  shrubs  are  denser  and  larger,  and  some  trees 
are  present.     Reprinted  from  the  Journal  of  Morphology. 


2.      SWEET-CLOVER   ASSOCIATION 

(Fig.  158)  (55) 
Under  the  condition  described  above,  the  water  of  rainfall,  as  well 
as  the  slumping,  reduces  the  angle  of  slope,  and  the  bluff  becomes  more 
and  more  stable.  Some  of  the  clods  of  turf  from  the  top  of  the  bank 
stop  half  way  down  the  slope.  The  bluff  begins  to  support  a  few  xero- 
phytic  plants,  such  as  the  sweet  clover,  asters,  etc. 


212 


DRY  AND  MESOPHYTIC  FOREST  COMMUNITIES 


^v  \A/>-V/ 


60   "'i^^B  iPj^> 


161 


162  163  164 

Life  History  of  the  Clay-Bank  Tiger  Beetle 

(Reprinted  from  the  Journal  of  Morphology) 

Fig.  159. — From  left  to  right — the  ventral,  side,  and  dorsal  view  of  the  oviposi- 
tor of  the  bluff  tiger-beetle  (jCicindela  limhalis)  with  segments  numbered;  3  times 
natural  size. 

Fig,  160. — ^The  egg  of  the  same  in  the  hole  in  the  ground  made  b}'  the  ovi- 
positor; i|  times  natural  size. 

Fig.  161. — ^The  egg;  3I  times  natural  size. 

Fig.  162. — 'The  larva,  side  view;  h,  hooks;  3  times  natural  size. 

Fig.  163. — -The  anterior  half  of  the  larva:  an,  antennae;  mp,  maxillary  palp; 
m,  mandible;  0,  ocelli;  3  times  natural  size. 

Fig.  164. — ^The  pupa;  3  times  natural  size. 


Fig.  165. — ^The  burrow  of  C.  litnbalis,  pupal  cell;  ^  natural  size. 


ox  CLAY 


213 


c)  Subterranean-ground  stratum. — Perhaps  the  most  characteristic 
animal  of  the  steep  bluff  is  the  bluff  tiger-beetle  (55,  151)  {Cicindela 
purpurea  limhalis)  (Figs.  159-67).  In  the  open  places  of  this  stage,  the 
larvae,  which  live  in  curved  cylindrical  burrows  (Figs.  165,  166),  are 
common. 

The  female  beetle  is  provided  with  an  ovipositor  (Fig.  159)  adapted 
to  making  small  holes  in  the  clay  in  which  eggs  are  laid  (Figs.  160,  161). 


Clay-Bank  Inhabitants 
Fig.  166. — View  of  larval  burrow  of  the  tiger-beetle;   natural  size. 
Fig.  167. — The  adult  tiger-beetle  {Cicindela  limhalis);   about  twice  natural  size. 
Fig.  168. — The  clay-bank  spider  {Pardosa  lapidicina). 
Fig.  169. — A  snail  of  the  shrub  stage  {Polygyra  monodon);  enlarged. 
Fig.  170. — IhesnaW  {Polygyra  thyroides);  enlarged. 

The  larva  (Figs.  162,  163)  on  hatching  from  the  egg  digs  a  burrow  in  the 
position  of  the  ovipositor  hole.  The  eggs,  which  are  laid  in  June,  hatch 
in  two  weeks  and  the  larvae  live  in  the  spot  where  the  eggs  were  laid 
for  one  year,  and  transform  into  pupae  (Fig.  164)  in  the  ground  in  an 
especially  prepared  cavity  (Fig.  165).     The  adult,  which  is  a  reddish- 


214  J^Ry  ^^VZ)  MESOPHYTIC  FOREST  COMMUNITIES 

green  form  (Fig.  167),  appears  in  the  autumn  and  lives  over  winter  in 
the  ground  (151). 

The  tiger-beetle  larvae  are  found  on  the  bare  spots  and  sometimes 
among  the  sweet  clover  (eggs  are  laid  before  the  clover  is  full  grown). 
They  feed  on  any  animals  that  crawl  over  the  clay  within  reach — any 
that  we  mentioned  may  fall  victims. 

As  physiographic  processes  go  on,  we  find  that  more  animals  make 
their  appearance,  bristle-tails  creep  out  of  the  cracks  in  early  spring,  and 
occasional  slugs  and  geophilids  are  found  hiding  under  clods.  A  large 
black  spider  {Pardosa  lapidicina)  (138)  (Fig.  168)  and  many  smaller 
species  are  present  also.  More  rarely  one  of  the  land  snails  {Pyramidula) 
is  present  at  this  time  of  year,  crawling  about  under  the  dead  vegetation. 
The  mud-dauber  wasp  (Pelopoeus  cementarius)  secures  its  mud  (40) 
and  the  Carolina  locust  {Dissosteira  Carolina)  probably  breeds  here. 

b)  Field  stratum.— Vnder  such  conditions,  as  summer  advances  the 
sweet  clover  grows  up,  and  as  soon  as  it  is  of  considerable  size  it  is 
attacked  by  aphids,  which  form  the  basis  for  a  small  consocies  of  inter- 
dependent animals.  Many  coccinelids  come  to  feed  on  aphids,  and 
parts  of  adult  coccinelids  have  been  found  in  the  burrows  of  the  tiger- 
beetle  larvae.  The  golden-eyed  lacewing  {Chrysopa  oculata)  deposits 
stalked  (p.  291)  eggs  on  the  plant;  soon  its  larvae — the  aphis-lions — 
are  devouring  aphids,  as  do  also  the  larvae  of  syrphus  flies  (164). 

Crab-spiders  {Runicina  aleatoria,  Misumena  vatia)  (138)  lie  in  wait 
in  the  clover  flowers  and  thus  capture  the  nectar-  and  pollen-seeking 
flies,  such  as  ]Eristd%s  tenax  (Fig.  271,  p.  270)  and  Syrphus  ribesli  Lin. 
(165).  The  common  plant-bug  {Adelphocoris  rapidus)  (Fig.  262,  p.  266) 
is  especially  abundant  in  autumn.  The  honey-bee  {Apis  mellifera)  and 
a  bumblebee  {Bombus  americanorum)  come  in  numbers  for  nectar  and 
pollen.  Grasshoppers,  such  as  Scudderia,  Melanoplus  femur-rubruni, 
etc.,  are  common,  and  when  young  may  fall  prey  to  spiders  such  as  orb- 
weavers  (Epeira  trivittata).  Parasitic  hymenoptera  {Pimpla  conquisitor 
Say)  are  also  common. 

3.      SHRUBS   ASSOCIATION    (a   FOREST    MARGIN   SUB-FORMATION ) 

A  little  humus  accumulates  locally  through  the  decay  of  sweet 
clover.  The  roots  of  plants  in  the  soil  and  the  undecayed  trunks  of 
the  sweet  clover  hold  this  and  the  mineral  soil  in  place  against  the 
action  of  the  rain  as  it  falls  on  the  slope.  Conditions  become  ripe 
for  the  germination  of  the  seeds  of  other  plants  and  for  the  breeding 
of  other  animals.     Shrubs,  such  as  the  willow  and  shad-bush,  appear 


ON  CLAY  215 

as   scattered  individuals  here   and   there,   and  bring  with  them  new 
conditions  and  animal  forms. 

a)  The  subterranean-ground  stratum. — In  addition  to  Pyramidula 
mentioned  above,  other  snails  appear,  especially  in  the  more  moist  spots 
on  the  bank.  These  are  Zonitoides,  Polygyra  monodon  (Fig.  169), 
and  P.  thyroldes  (Fig.  170).  Centipedes  (Geophilus)  and  millipedes 
(Polydesmidae)  become  more  numerous,  while  the  spiders  {Pardosa 
lapidicina)  (Fig.  168),  the  tiger-beetle  larvae,  and  other  soil-inhabiting 
forms  decrease. 

b)  Field  stratum. — The  field  stratum  of  the  shrub  stage  does  not 
differ  strikingly  from  the  preceding,  as  it  consists  mainly  of  plants  of 
the  earlier  stage  scattered  among  the  shrubs. 

c)  Shrub  stratum. — Here  we  have  the  characteristic  inhabitants  of 
shrubs.  On  the  young  aspens  and  willow  are  the  larvae  of  the  viceroy 
butterfly  (163).  The  common  gall  on  the  willow  is  the  pine-cone  gall, 
caused  by  Cecidomyiidae  (137).  Beneath  the  leaves  of  the  cone  we  have 
found  long  slender  eggs  of  some  orthopterous  insect  (probably  Xiphidium 
ensiferum)  (40,  p.  428).  We  have  no  record  of  the  nests  of  birds,  but 
many  of  the  forest  margin  birds  nest  here  (see  pp.  274-75  and  Table 
LXIV,  p.  277). 

4.      YOUNG   FOREST   STAGE 

(Fig.  171) 

Shrubs  and  seedlings  of  trees  become  more  and  more  numerous. 
The  sweet  clover  and  most  of  the  animals  associated  with  it  disappear. 
Young  trees,  such  as  oak,  hickory,  hop,  hornbeam,  etc.,  grow  and  usually 
give  rise  to  a  sapling  forest. 

a)  Subterranean-ground  stratum. — -This  stratum  has  all  the  characters 
of  the  more  dense  and  mesophytic  forest  ground  stratum  and  largely  be- 
cause of  the  springy  character  of  the  bluff  which  supplies  much  moisture. 
The  woodchuck  {Marmota  monax)  (142)  sometimes  digs  in  these  banks. 
In  the  open  places  in  which  small  areas  of  soil  are  covered  with  only  a 
few  leaves  we  find  the  larvae  of  the  green  forest  tiger-beetle  (Cicindela 
sexguttata)  (55,  151)  which  lays  eggs  in  shaded  places  (Figs.  172,  173). 
Under  the  leaves  the  snails,  which  were  recorded  in  the  younger  stages, 
and  sowbugs  are  present.  We  find  snails  and  slugs  {Polygyra  profunda 
[Fig.  220,  p.  237]  and  albolabris  [Fig.  240,  p.  243],  Philomycus  caro- 
linensis  [Fig.  231,  p.  241]),  which  are  commonly  abundant  in  dense 
woods.  The  Myriopoda  are  also  more  numerous  and  belong  to  different 
species.     Fontaria  corrugate  (Fig.  218,  p.  237),  which  has  the  margins 


2l6 


DRY  AND  MESOPHYTIC  FOREST  COMMUNITIES 


The  Bluff  Forest 

Fig.  lyi.-^An  open  place  in  the  oak  and  hickory  forest  of  a  Tennessee  mountain- 
side, a  typical  green  tiger-beetle  {Cicindela  sexgutlala)  habitat.  The  individuals  were 
seen  copulating  on  the  log  in  the  foreground.  The  general  aspect  is  very  similar  to 
that  of  the  bluff  forest.     (Reprinted  from  the  Journal  of  Morphology.) 


172  173 

Fig.  172. — The  black  dots  represent  the  distribution  of  the  larvae  of  C.  sexguttata 

from  eggs  laid  in  a  cage.    The  larvae  are  in  the  exact  position  in  which  eggs  are  laid . 

The  stippled  area  is  in  shadow  in  the  middle  of  the  day. 
Fig.  173. — Diagram  of  a  burrow  of  Cicindela  sexguttata. 


ON  ROCK 


217 


of  the  segments  striped  with  yellow,  is  one  of  the  most  characteristic 
of  moist  woods,  while  others  {Geophilns  riibens  and  Lysiopetalum  lac- 
tarium)  are  not  uncommon.  Ground  beetles  {Calathus  gregarius  Say) 
and  bugs  {Reduviolus  subcoleoptratus)  occur.  In  logs  of  fallen  basswood 
we  found  the  larvae  of  Tenehrionidae  and  Cerambycidae  and  of  horntails, 
the  burrowing  hymenoptera,  and  the  Mycetophilidae  larvae  (Sciara) 
(Fig.  174)  (165). 

c)  Field  stratum  and  shrub  stratum. — The  field  stratum  has  been  but 
little  studied.  We  have  taken  a  few  Scudderia  nymphs,  some  spiders, 
and  bugs,  but  no  adequate  study  has  been  carried  on. 

d)  Tree  stratum. — This  has  likewise  been  but  little  studied,  but  in 
these  young  forests,  while  the  ground  stratum  is  like  that  in  the  older 
forest,  the  tree  stratum  is  poorly  de- 
veloped because  the  trees  are  short 
saplings.  As  time  goes  on,  however, 
the  forest  becomes  more  dense.  Such 
a  forest  may  be  seen  on  the  bluff  at 
Lake  Blufif,  111. 


5.   OTHER  BARE  CLAY  FORESTS 

Other  bare  clay  young  forests  may 
be  seen  along  the  dumps  of  the  drainage 
and  Chicago-Michigan  canals  at  Summit. 
Here  we  find  practically  the  same  stages 
as  at  Glencoe  on  the  lake  bluff.  There 
are  the  steep  clay  bluffs  with  no  perma- 
nent residents,  the  semi-stable  bluffs,  or 
weed-occupied  areas.  These  are  like  the 
semi-stable  bluffs  at  Glencoe  but  the  tiger-beetle  is  another  species  and 
selects  more  nearly  level  places;  otherwise  it  is  very  similar  in  habits. 

The  shrub  stage  occurs  but  is  without  the  snails,  since  the  ground- 
water level  is  lower  and  the  moisture  in  the  soil  of  the  lake  bluff  is  wanting 
here.  This  causes  the  development  of  the  ground  stratum  to  lag  behind, 
while  it  is  in  advance  in  the  bluff  forests.  Accordingly  we  find  a  sapling 
forest  made  up  largely  of  cottonwoods.     This  has  not  been  studied. 


Fig.  174. — One  of  the  fungus 
gnats  {Sciara  sp.)  the  larvae  of 
which  are  commonly  found  under 
the  bark  of  trees,  feeding  on  fungus. 


HI.    Forest  Communities  on  Rock 
(Station  55) 
The  rock  exposures  near  Chicago  are  not  numerous,  and  we  have 
studied  only  those  at  Stony  Island.     There  the  bare  rock  is  inhabited 


2l8  DRY  AND  MESOPHYTIC  FOREST  COMMUNITIES 

by  incidental  forms,  such  as  the  Carolina  locust  {Dissosleira  Carolina  ?) 
(40),  with  occasionally  the  red-legged  locust  (Melanoplus  femur- 
rubrum)  and  the  two-Hned  locust  (Melanoplus  bivittatus).  Under  rock 
fragments  we  took  the  ground  beetle  (Anisdactylus  inter pundatus)  and 
the  common  cricket  {Gryllus  pennsylvanicus) .  Hancock  (40)  states 
that  the  smooth  cockroach  (Ischnoptera  inaequalis  Sauss)  and  the  large 
cockroach  (/.  major  Sauss)  occur  in  such  situations.  We  found  the  nest 
of  a  spider  {Agelena  naevia)  attached  to  one  of  the  loose  rocks. 

Other  stages  have  been  studied  only  superficially.  In  the  cracks 
and  crevices  of  rocks  and  rock  piles,  shrubs  and  vines  grow  and  the 
young  forest,  field,  and  shrub  strata  have  all  the  appearance  of  the 
shrub  stage  on  clay  at  Glencoe.  The  animals  are  for  the  most  part  those 
common  to  thickets. 

IV.    Forest  Communities  on  Sand 

In  chap,  iii,  pp.  46,  47,  we  discussed  sand  areas  and  their  distribu- 
tion. In  chap,  viii  we  noted  the  series  of  ponds  and  ridges  with  a  little 
regarding  their  origin  (pp.  136-40) .  Their  general  relations  are  indicated 
by  Figs.  83,  p.  137,  and  84,  p.  139.  It  appears  that  the  margin  of  the  lake 
may,  under  conditions  of  rapid  recession,  become  the  margin  of  an  inland 
pond.  Under  condition  of  slower  recession  this  belt  may  be  buried  and 
hence  come  to  lie  beneath  such  belts  as  lie  farther  inland.  Since  the 
sand  areas  about  Chicago  represent  all  the  stages  in  the  development 
of  forests,  beginning  with  the  bare  sand  and  ending  with  the  beech 
forest,  it  is  my  purpose  in  the  remainder  of  this  chapter  to  follow  the 
animal  associations  and  formations  of  forest  development.  Some  of  the 
stages  will  be  taken  from  till  areas,  but  this  is  because  these  stages  are 
more  extensive  than  the  corresponding  stages  on  the  sand  deposits. 

The  chief  stages  are  the  wet  sand  of  the  water  margin,  the  middle 
beach,  the  cottonwoods,  the  old  cottonwoods  and  pine  seedlings,  the 
pines,  the  black  oak,  the  black  oak  and  white  oak,  the  black  oak-white 
oak-red  oak,  the  red  oak-white  oak-hickory,  the  basswood-red  oak- 
white  oak-maple  in  moister  places,  and  the  beech  and  maple. 

I.      THE   WATER   MARGIN   ASSOCIATION 

(Stations  56,  58;  Table  XXXVIII) 

One  morning  early  in  June,  we  walked  along  the  beach  of  Lake 

Michigan  for  a  mile  and  a  half,  for  the  particular  purpose  of  studying 

the  animals  of  the  zone  within  the  reach  of  waves.     Animals  were  few, 

only  stragglers  of  the  regular  residents  which  we  have  noted  on  p.  181. 


WATER  MARGIN  219 

The  day  was  warm  and  a  strong  southeast  wind  was  blowing.     In  mid- 
afternoon  there  was  a  small  shower  and  the  wind  changed  to  a  strong 
northeaster.     At  4  p.m.  we  paid  another  visit  to  the  beach.     The  waves 
were  rolHng  moderately  high  and  the  beach  was  covered  with  a  host  of 
insects,  chiefly  alive,  though  many  were  dead.     The  beach  was  lined 
with  live  forms  crawling  away  from  the  water.     Often  the  live  ones 
were  still  clinging  to  small  sticks  upon  which  they  had  floated  ashore 
by  the  fifties.     These  insects  represented  all  orders,  belonging  to  various 
habitats  near  the  lake.     There  were  large  forest  margin  bugs,  potato- 
beetles,  lady-beetles,  horseflies,   robber-flies,   butterflies,  water,  marsh, 
prairie,  and  forest  inhabitants  which  had  been  blown  in  the  lake  in  the' 
forenoon.     With  them  were  occasional  fish,  some  with  large  round  scars 
showing  the  work  of  the  lampreys  (166);   others  that  had  evidently  died 
from  other  causes.     On  other  occasions  dead  muskrats,  dogs,  cats,  birds 
of  all  kinds  have  been  found  in  these  lines  of   drift   (167).     On  one 
occasion,  birds,   chiefly  downy  woodpeckers,  were  so  numerous  that 
one  could  almost  step  from  one  to  the  other,  had  they  been  equally 
spaced  over  the  half-mile  of  beach  upon  which  they  were  strewn.     Need- 
ham  (168)  has  studied  the  drift  and  gives  an  account  of  the  numerous 
beetles  that  came  ashore. 

In  a  few  days  after  such  a  storm,  one  finds  the  various  insects  that 
washed  ashore  either  lying  dead,  or  alive  under  the  chips,  sticks,  and 
carcasses  which  came  with  them.  Flesh-flies  detect  the  presence  of  the 
food  very  quickly,  and  often  come  to  dead  fish  inside  of  ten  or  fifteen 
minutes  (169).  These  flies  belong  to  the  families  Sarcophagidae  and 
Muscidae.  As  a  result  of  storms  which  float  the  bodies  of  animals 
ashore  from  time  to  time,  the  flies  always  find  a  sufiicient  quantity  of 
decaying  flesh  to  maintain  the  species.  The  flies  are  in  competition  with 
a  large  number  of  scavenger  beetles:  e.g.,  a  hister  {Saprinus  patruelis 
Lee.)  which  feeds  on  carrion  {Stereopalpus  hadiipennis  Lee).  Several 
species  of  rove-beetle  complete  a  partial  list  of  the  other  scavengers 
usually  more  or  less  abundant  on  the  shore.  The  larvae  of  Dermestidae 
have  been  found  under  the  dry  remains  of  fish  which  had  been  worked 
over  by  the  carrion-feeders. 

Preying  upon  these  and  upon  the  insects  that  come  ashore  are  the 
tiger-beetles  (Cicindela  kirticollis  and  cuprascens)  (151,  170)  which  pick 
up  the  flies  that  they  often  are  able  to  seize  while  alighting  on  the  ground. 
They  also  capture  the  maggots  of  the  flies  when  they  leave  the  carrion, 
and  the  lady-beetles  and  other  small  insects  which  come  ashore.  Several 
species  of  the  ground  beetles  and  occasional  shore  bugs  (Saldidae)  are 


220  DRV  AND  MESOPHYTIC  FOREST  COMMUNITIES 

found,  while  the  digger-wasps  and  robber-flies  of  the  beach  farther  back 
come  here  for  flies  and  other  prey.  The  spotted  sandpiper  picks 
maggots  from  the  bodies  of  dead  fishes.  Mr.  I.  B.  Myers  states  that 
skunks  visit  the  beach  in  the  night  and  feed  upon  the  drift. 

2.      MIDDLE   BEACH  ASSOCIATION 

(Stations  57,  58,  716)  (Fig.  175) 

The  belt  within  the  reach  of  ordinary  waves  is  usually  wet.  The 
belt  a  little  higher  up,  farther  from  the  shore,  is  characterized  by  more 
permanent  residents.  From  the  often  wet  margin  to  the  first  cotton- 
woods  is  the  middle  beach  (Fig.  175). 

This  middle  beach  is  usually  dry  in  summer  but  is  reached  by  the 
waves  of  severe  storms  and  often  covered  by  snow  and  ice  to  great 
depths  during  the  winter.  It  is  the  final  lodging-place  for  the  driftwood 
which  stops  temporarily  farther  out.  This  belt  arises  in  the  place  of 
the  preceding  through  the  former  being  buried  by  the  depositions  of 
sand.  In  digging  into  the  sand  here  or  elsewhere  one  usually  encounters 
wood  and  other  traces  of  organic  matter, 

a)  Subterranean-ground  stratum. — In  the  lower  places  where  the 
ground  is  usually  moist,  we  find  the  larvae  of  Cicindela  hirticollis  (170) 
which  live  in  straight  cylindrical  vertical  burrows  about  6  in.  deep.  On 
higher  ground,  where  there  is  the  beginning  of  the  incipient  dunes,  are 
the  occasional  larvae  of  the  white  tiger-beetle  {Cicindela  lepida)  and  the 
burrowing  spider  {Geolycosa  pikei),  which  has  a  burrow  similar  to  the 
tiger-beetles,  but  larger,  and  always  distinguished  by  the  presence  of  a 
tubular  web  at  the  entrance.  Burrowing  beneath  the  sand  is  the  white 
carabid  {Geopinus  incrassatusDey)  and  termites  or  white  ants.    The  latter 

Inhabitants  of  the  Middle  Beach 

Fig.  175. — General  view  showing  the  line  of  cottonwoods  and  the  scattered 
driftwood. 

Fig.  176. — The  larva  of  one  of  the  cabbage  butterflies  {Pieris  protodice  Bd.); 
found  on  sea  rocket;  much  enlarged. 

Fig.  177. — Pupa  of  the  same. 

Fig.  178. — A  logon  the  beach;  favorite  habitat  of  the  termites  (Termesflavipes). 
Fig.  179. — Termites;  a,  queen;  6,  nymph  of  young  female;  c,  worker;  </,  soldier; 
twice  natural  size  (after  Howard  and  Marlatt,  Bull.  4,  Div.  Ent.,  U.S.  D.  Agr.). 
Fig.  180. — The  older  cottonwoods  of  the  cottonwood  belt. 
Fig.  181. — The  adult  white  tiger-beetle  (Cicindela  lepida);  twice  natural  size. 
Fig.  182. — The  burrow  of  the  larva  of  the  white  tiger-beetle. 


MIDDLE  BEACH 


221 


75 


•Bfl^' 


■^ 


78 


/  179 


) 


81 


*?:■;.•  J. ',.^5.  .A; 


82 


Inhabitants  of  the  Middle  Beach 


222  DRY  AND  MESOPHYTIC  FOREST  COMMUNITIES 

feed  on  decaying  wood  (Fig.  178)  and  make  their  way  to  the  under  side 
of  wood  lying  on  the  beach  (Fig.  179).  The  bank  swallow  oft^n  nests 
in  the  sides  of  vertical  sandbanks.  Under  the  driftwood  we  find  the 
scavengers  and  predatory  species  of  the  preceding  belt.  They  spend 
their  time  here  when  the  beach  is  not  well  covered  with  food.  The 
sand-colored  spider  {Trochosa  cinerea)  (138)  is  a  regular  resident.  The 
common  toad  finds  shelter  beneath  the  driftwood  during  the  day,  going 
forth  in  search  of  food  at  night.  After  sleeping  near  the  beach  one  night 
we  found  the  sand  about  where  we  had  lain  crossed  and  recrossed  by  the 
tracks  of  the  toads  and  other  smaller  animals,  such  as  beetles,  spiders, 
etc.  The  toad  finds  food  abundant  near  the  shore.  The  white-footed 
mouse  occasionally  nests  here  under  the  largest  driftwood.  The  spotted 
sandpiper  and  piping  plover  nest  here  occasionally. 

h)  Field  stratum. — There  are  occasionally  very  young  seedling 
cottonw'oods.  Sea  rockets  and  some  other  plants  grow  in  this  belt. 
Occasionally  we  find  the  larvae  of  a  cabbage  butterfly  (Pieris  protodice 
Bdv.)  (171)  on  the  sea  rocket  (Figs.  176,  177).  There  is  no  shrub  or 
tree  stratum. 

3.      THE   WHITE  TIGER-BEETLE    OR    COTTONWOOD   ASSOCIATION 

(Stations  57,  58,  59;  Tables  L,  LVI,  LVII) 
(Fig.  180)  (115) 

This  begins  with  the  line  of  young  cottonwoods  which  we  see  in 
Fig.  175.  The  beach  belt  sometimes  overlaps  it  because  the  large 
driftwood  is  sometimes  mixed  with  the  cottonwoods.  The  cottonwood 
belt  is  underlaid  by  the  two  preceding,  and  has  succeeded  them. 

a)  Subterranean- ground  stratum. — 'Here  the  white  tiger-beetles  (Figs. 
181,  182)  reach  their  maximum  abundance  and  the  openings  of  their 
cylindrical  burrows  are  numerous;  the  termites  continue  wherever  there 
is  wood  for  them  to  feed  upon;  the  burrowing  spider  is  commoner 
here  than  in  the  preceding  zone  (172).  This  is  pre-eminently  the  zone 
of  digger-wasps  (173).  Here  the  holes  of  Microbemhex  monodonta 
(Fig.  183)  are  numerous.  This  species  is  somewhat  gregarious,  the  bur- 
rows usually  being  in  groups.  They  probably  store  their  nests  with  flies 
secured  often  from  the  beach.  Another  larger  bembex  (Figs.  184,  185) 
{B.  spinolae)  also  stores  its  nest  with  flies.  Anoplius  divisus,  the 
black  digger,  stores  its  nest  with  spiders.  The  velvet  ant  {Mutilla 
or  native  ntr  is)  is  present.  Dielis  plumipes  appears  in  May  and  lays  its 
eggs  in  the  sand. 

The  robber-flies  {Erax)  (Fig.  186)  (165)  {Promachus  vertebratus)  (Fig. 
187)  are  common;    their  larvae  live  in  the  sand  as  parasites  on  other 


COTTONWOOD  ASSOCIATION 


223 


species.  Some  bee-flies  {Exoprospa)  (Fig.  188)  lay  their  eggs  at  the 
entrances  of  the  burrows  of  Microbembex.  The  roots  of  the  beach  grasses 
are  probably  attacked  by  the  larvae  of  snout-beetles  (Sphenophorus) 
(Fig.  189)  (174)  of  which  several  species  are  very  common  in  the  vicinity. 
The  white  grasshopper  {Trimerotropis  maritima)  (40)  and  the  white  tiger- 
beetle  {Cicindela  Icpida)  are  most  characteristic.  The  long-horned 
locust  {Psinidia  fenestralis)  (Fig.  189)  occurs  commonly. 

b)  Field  stratum. — The  field  stratum  is  made  up  of  animals  that 
occupy  the  grasses,  sagebrush,  and  a  few  other  xerophytes.     Animals 


184 


'.3ki&^:^.>^ 


183 


Diggkr-W'asps  of  the  Cottonwood  or  White  Tiger-Beetle  Association 

Fig.  183. — Photograph  of  a  number  of  the  burrows  of  one  of  the  digger-wasps 
{Microbembex  mo>wdoiUa)  at  Pine,  Ind. 

Fig.  184. — A  digger-wasp  {Bembex  spinolac);  about  twice  natural  size. 

Fig.  185. — A  sectional  drawing  of  a  burrow  of  the  digger-wasp  {Bembex  spinolae); 
reduced  (after  the  Peckhams,  Wis.  Geol.  and  N.  H.  Surv.). 


are  few.  An  occasional  red-legged  locust  {Melanopliis  femur-nibrum) 
occurs  here.  Midges,  mosquitoes,  and  the  flies  which  breed  on  the  beach 
rest  on  the  leeward  side  of  the  grasses  (169).  Various  native  sparrows 
are  common  in  fall,  feeding  on  grass  and  weed  seeds. 

c)  Shrub  stratum. — -On  the  young  cotton  woods  we  find  the  crab- 
spider  (Philodromus  alaskensis) ,  often  with  its  appendages  stretched  out 
on  the  petiole  or  midrib  of  a  leaf.  The  animals  feeding  on  the  cotton- 
wood  here  are  few.     In  early  spring  the  willow  blossoms  are  frequented 


2  24 


DRY  AND  MESOPHYTIC  FOREST  COMMUNITIES 


by  pollen-gathering  insects  (Andrenidae,  Apidae,  syrphus  flies,  etc.). 
The  kingbirds  feed  on  these  insects;  one  article  of  their  diet,  the  robber- 
flies,  is  always  common.  A  chrysomelid  beetle  {Disonycha  quinqiievittata) 
commonly  feeds  upon  the  willow.     The  cherry  is  attacked  by  aphids 


Fig.  i86. — A  robber-fl>'  {Erax  sp.);  3  times  natural  size  (after  Williston). 


187 


Fig.  187.  —  Robber-fl>'  {Pro- 
machus  vertebratus  Say);  natural 
size  (after  Washburn  from  Willis- 
ton). 

Fig.  188. — A  bee-fly  {Exoprosopa 
sp.);  i^  times  natural  size  (from 
Williston  after  KeUogg). 


which  attract  the  Coccinellidae,  and  the  syrphus  flies.     Cherries  are 
eaten  by  many  birds. 


COTTONWOOD  ASSOCIATION 


225 


d)  Tree  stratum.— The  cottonwood  is  attacked  by  many  borers. 
The  most  characteristic  is  Plectrodera  scalator,  which  is  not  common. 
There  are  few  leaf-feeders  excepting  two  gall  aphids;  the  petiole  gall  is 
due  to  the  work  of  Pemphigus  populicaulis,  and  the  terminal  gall  to 
Pemphigus  vagabundus  (137).  These  occur  on  the  cottonwoods  along 
the  lake  rarely,  being  more  abundant  farther  inland,  where  they  are 
protected  from  the  severity  of  winter.  The  osprey  nests  in  trees,  and  the 
tree-swallow  in  the  dead  ones. 

We  have  noted  that  this  association  often  arises  through  the  burying 
of  the  preceding  one.  Deposition  of 
sand  is  the  chief  cause  of  succession 
up  to  this  point.  When  cottonwoods 
and  grasses  begin  to  grow  and  digger- 
wasps  begin  to  burrow,  organic  mat- 
ter is  continually  added  to  the  soil. 
The  grasses  die  down  from  time  to 
time,  the  roots  and  leaves  of  the 
shrubs  and  other  plants  add  humus. 
The  myriads  of  digger-wasps  which 
go  elsewhere  (probably  commonly  to 
the  beach)  for  the  animals  with  which 
to  store  their  nests  add  a  large  amount 
of  organic  matter  at  a  depth  of  a  few 
inches.  The  grasses  bind  the  dune 
sand;  the  conditions  become  favorable  for  other  plants, 
stage  the  bunch-grass  and  seedlings  of  pines  appear. 


Fig.  189. — The  long-horned  locust 
(Psinidia  fenesiralis)  (after  Lugger). 


At  such  a 


4.      TRANSITION   BELT 

(Station  58;  Table  L)  (Fig.  190)  (115,  170) 

The  stage  of  mixed  pine  seedlings,  old  cottonwoods,  and  the  begin- 
ning of  the  bunch-grass  constitutes  a  well-marked  belt.  Along  the 
shore,  from  Indiana  Harbor  to  Gary,  there  was  formerly  a  ridge  upon 
which  the  lakeward-facing  side  supported  the  typical  community  of  the 
cottonwoods  and  the  landward  side  the  transitional  belt.  When  one 
crosses  to  the  landward  side  of  such  a  ridge  he  notes  a  change  in  the 
animals.  The  white  tiger-beetles  and  the  maritime  grasshopper  are 
practically  absent.  Digger-wasps  are  abundant.  The  larvae  of  the 
large  tiger-beetle  {Cicindela  formosa  generosa)  (Figs.  191-193)  with  their 
pits  and  crooked  holes  are  added,  but  they  rarely  invade  the  dense  pine 
areas.     Another  grasshopper  (Fig.   194)   {Melanoplus  atlanis)  and  an 


226 


DRY  AXD  MESOPHYTIC  FOREST  COMMUNITIES 


I'iG.  190. — The  coUonwood  and  young  pine  area  at  Buffington,  Ind. 
Fig.  191. — The  burrow  of  one  of  the  tiger-beetles  resident  here. 
Fig.  192. — The  same  opened,  showing  the  stove-pipe  form  of  burrow  opening 
into  the  side  of  the  pit  shown  in  Fig.  191. 

Fig.  193. — The  adult  beetle  {Ciciudela  formosa  geucrosa). 


PINE  ASSOCIATION  227 

occasional  M.  angustipennis  are  added   (40).     The  burrowing  spider 
{Geolycosa  pikei)  (Fig.  200,  p.  230)  continues  in  the  open  places. 

5.      THE  CICINDELA   LECONTEI  OR   PINE   ASSOCIATION 

(Stations  57,  58,  59;  Tables  L,  LI,  LVI,  LVIII)  (Figs.  201)  (115,  170) 
a)  Subterranean-ground  slratum.—Uere  we  find  the  larva  of  the 
bronze  tiger-beetle  (Cicindela  scutellaris  lecontei)  (170),  with  its  straight 
cylindrical  burrow.  Several  digger-wasps  of  the  earlier  sta-e  "are 
recorded  as  continuing.  The  ant  {Lasius  niger  americanus)  nests 
beneath  the  sand  and  was  seen  swarming  in  early  September  The 
burrowing  spider  continues  and  an  occasional  cicada  lives  deep  beneath 
the  sand.  The  six-lined  lizard  {Cnemidophorus  6-lineatus),  the  blue 
racer,  and  the  pond  turtle  {Chrysemys  marginata)  all  bury  their  eggs 
beneath  the  sand.     There  is  an  occasional  thirteen-lined  ground  squirrel 


Fig.  194.— The  lesser  migratory  locust  {Melamplus  atlanis)  (after  Lugger). 

{Citellus  13-Uneatus)  (162),  though  it  is  never  common.  The  surface 
of  the  ground  is  frequented  by  the  adults  of  the  tiger-beetles  digger- 
wasps,  the  six-lined  lizard,  and  the  blue  racer  (157).  The  grasshopper 
of  the  transition  belt  continues  and  two  others  are  added,  so  that  we 
have  the  long-horned  locust,  the  narrow-winged  locust,  the  lesser  locust 
the  mottled  sand-locust  {Sparagemon  wyomingianum  Thom.),  and  sand- 
locust  {Ageneotettix  arenosus)  (40).  The  ruffed  grouse  nests  here  occa- 
sionally. 

b)  Field  stratum.— Arabis  lyrata  is  a  common  herb.  Shull  (175) 
found  that  the  larva  of  a  cabbage  butterfly  feeds  upon  this  He 
watched  a  larva  crawl  on  one  of  the  bunches  of  bunch-grass  for  six 
hours  before  it  began  to  spin  the  bed  of  silk  preparatory  to  pupating. 
This  was  about  2  in.  above  the  ground.  Midges  and  mosquitoes  are 
common  and  dragon-  and  damsel-flies  are  nearly  always  in  evidence 
resting  on  the  grasses  and  herbs  and  picking  up  the  midges  and  mos- 
quitoes while  on  the  wing.  Occasional  Monardas  support  crab-spiders 
which  resemble  the  blossoms  closely  {Dictyna  foliacea).  The  flowers 
are  visited  by  bees  and  flies. 


228 


DRV  AND  MESOPHYTIC  FOREST  COMMUNITIES 


c)  Shrub  stratum. — Here  we  have  the  young  pines,  the  juniper,  and 
the  willows.  From  the  evergreens  we  secured  several  spiders  {Philo- 
dromus  alaskensis,  Dendryphantes  octavus,  Theridium  spirale,  and 
Xysticus  formosus)  (172),  and  with  them  sometimes  an  assassin-bug 
(Diplodius  luridtis).  On  the  willows  are  some  characteristic  willow- 
feeders,  but  they  appear  to  prefer  the  more  mesophytic  depression 
shrubs. 


Inhabitants  of  the  Pine 

Fig.  195. — The  nest  of  the  kingbird  {Tyranniis  tyraiimis  Linn)  in  a  pine  tree. 
The  nest  is  made  from  the  string  of  a  fisherman's  net. 

Fig.  196. — The  pitch  mass  of  the  pitch-moth  (Evetria  comsiockiana?);  twice 
natural  size. 

Fig.  197. — The  larva  removed  from  the  mass. 

Fig.  198. — The  larva  of  the  pine  engraver  beetle  {I ps  graudicoUis);  much 
enlarged. 

Fig.  199. — The  adult  of  the  same,  from  Finns  hanksiaita. 


d)  Tree  stratum. — The  pine  is  attacked  by  many  borers  and  few 
leaf- feeders.  Of  the  borers  several  broad-headed  grubs  have  been  taken. 
The  bark  beetle  {Ips  [Tomicus]  grandicollis)  (Figs.  198,  199)  (137)  is 
common  under  the  bark  of  dead  and  dying  trees,  especially  on  the  north 
side,  where  the  trees  stand  unprotected.     The  twigs  are  attacked  by  the 


BLACK-OAK  ASSOCIATION  229 

pitch-moth  (Evetria  comstockiana?)  (Figs.  196,  197)  (137)  which  feeds 
on  the  new  shoots,  covering  itself  with  a  tent  made  of  pitch  and  its  own 
excreta.  About  the  bases  of  the  needles,  or  where  pitch  is  exuding,  we 
often  find  small  larvae  resembling  Cecidomyiidae  fly  larvae,  but  we  have 
found  no  pitch-midges,  chrysomelid  flea-beetles,  spittle  insects,  or  other 
enemy  of  the  eastern  hard  pines  which  grow  in  thicker  stands.  More 
careful  study  of  these  trees  at  frequent  intervals  throughout  the  grow- 
ing season  would  probably  greatly  increase  the  list  of  both  borers  and 
leaf-feeders. 

The  hairy  and  downy  woodpeckers  nest  in  the  hollow  trees.  Their 
deserted  holes  are  later  used  by  the  black-capped  chickadee  and  the 
screech  owl.  Farther  north  the  pine  grossbeak  and  crossbill  nest  in  the 
live  pines.  The  golden-crowned  kinglet  and  the  black-throated,  green, 
and  pine  warblers  are  abundant  here  during  the  migration  period.  They 
nest  in  the  pines  farther  north,  and,  according  to  Butler  (108),  not  infre- 
quently at  the  head  of  Lake  Michigan.  Dr.  Stephens  photographed  a 
kingbird's  nest  made  from  cord  from  a  fisherman's  net  (Fig.  195). 

The  pines  prepare  the  way  for  the  oaks,  which  appear  first  as  seed- 
lings, usually  becoming  more  dense  with  time  and  finally  crowding  out 
the  pines. 

Moving  dunes  and  ''blowouts"  (depressions  in  the  sand  made  by 
wind)  are  common  at  the  head  of  Lake  Michigan.  The  latter  vary 
from  a  few  feet  square  and  a  few  inches  in  depth  to  some  scores  of  feet 
in  depth  and  diameter.  Dunes,  hundreds  of  feet  high,  move  from  place 
to  place.  On  these  the  bare-sand  conditions  of  the  cottonwood  and  pine 
associations  occur  in  areas  generally  dominated  by  black  oak.  Here  con- 
tinue the  animals  of  these  two  belts,  with  the  possible  exception  of  the 
maritime  locust.  The  typical  black-oak  forest  always  possesses  these 
"blowouts,"  but  surrounding  them  and  under  the  trees  we  note  the 
t>pical  herbaceous  and  shrub  growth,  and  it  is  with  this  and  the  oak? 
that  we  are  next  concerned. 

6.      THE   ANT-LION   OR   BLACK-OAK  ASSOCIATION 

(Stations  57,  60,  61,  62;  Tables  L,  LII,  LVI,  LIX) 
(Fig.  202)  (115,  170,  176) 
Among  the  black  oaks  are  open  spots  of  relatively  stable  sand. 
These  small  areas  may  possess  some  of  the  same  species  as  the  pine  areas, 
but  other  species  give  them  individual  character.  In  the  black-oak 
stage  proper,  bare  sand  is  limited.  The  bronze  tiger-beetle  {Cicindela 
scutellaris  lecontei)  (Fig.  204)  which  is  parasitized  by  the  larva  of  a  bee- 
fly  {SpogostyJum  anale)  (Fig.  205)  is  abundant  (151a.) 


230  DRY  AND  MESOPHYTIC  FOREST  COMMUNITIES 


Representatives  of  the  Pine  and  Black-Oak  Association 

Fig.  200. — The  burrow  of  a  ground  spider  (Gcolycosa  pikci) ;  about  natural  size. 
Fig.  201. — General  view  in  the  pines.     Fig.  202. — General  view  among  the  oaks. 
Fig.  203. — -The  ant-lion  and  the  pupa  and  adult  into  which  it  transforms. 
Fig.  204. — The  opening   of   the  burrow  of  the  bronze  tiger-beetle   (Ciciiidcla 
scutellaris  lecoutei) ;   natural  size. 

Fig.  205. — The  bee-fly  {Spogostyhim  aua/e);   twice  natural  size. 


BLA  CK-OA  K  A  SSOCIA  TION 


231 


a)  Subterranean-ground  stratum.— ^extmX  digger-wasps  and  para- 
sites not  found  in  the  earlier  stages  occur  among  the  more  closely  placed 
N'egetation  here  (Epeolus  pusillus,  a  parasite,  Specodes  dichroa,  and  Ody- 
uerus  a  nor  mis).  A  megachilid  or  leaf-cutter  makes  a  nicely  matched 
thimble-shaped  cell.  This  cell  is  placed  at  the  end  of  a  burrow  about 
2  in.  below  the  surface  of  the  sand.  The  burrow  is  about  4  in.  long.  The 
leaf-cutter  is  attacked  by  a  parasitic  bee  {Coeloi.xys  rufitarsus)  which 
lays  its  eggs  upon  the  larval  cell.  One  sunny  day  we  found  the  digger- 
wasp  (Ammopln'la  procera)  (173)  with  a  black-oak  caterpillar  (Nadata 


Representatives  of  the  Black-Oak  Community 

Fig.  206. — One  of  the  solitary  wasps  {Ammophila  procera),  with  the  oak-feeding 
larva  {Nadata  gibbosa),  which  it  has  carried  to  a  point  near  its  nest  and  laid  upon  the 
ground;  i|  times  natural  size. 

Fig.  207. — Female  crab  spider  {Misumcssus  asperatiis)  (after  Emerton);  enlarged. 

Fig.  208. — Male  of  same. 

Figs.  209a,  logb. — The  fiatbug  {Neuroctemis  simplex)  which  lives  under  the  bark 
on  the  dead  oaks.     209(2  is  a  side  view,  much  enlarged. 


gibbosa)  (Fig.  206)  (137).  When  first  observed,  the  larva  was  lying  on 
the  ground  and  the  wasp  was  moving  about  some  6  in.  away.  As  we 
approached,  the  Ammophila,  apparently  disturbed,  seized  the  large 
caterpillar  and  ran  into  the  adjoining  vegetation,  where  it  was  captured. 
All  the  forms  mentioned  as  breeding  beneath  sand,  feed  at  the  surface 
of  the  soil  or  upon  the  vegetation.  In  open  places  among  the  black 
oak  we  find  the  same  grasshoppers  as  in  the  earlier  stages.  The  hog-nosed 
snake  (40)  is  common;  it  spreads  and  flattens  out  its  head  when  dis- 
turbed; when  handled  roughly  it  often  goes  into  a  death  feint,  such  as 
the  oriental  snake-charmers  produce  in  their  poisonous  snakes  by  pres- 


232 


DRV  AND  MESOPHYTIC  FOREST  COMMUNITIES 


sure  on  the  back  of  the  neck.  In  this  state  it  can  be  handled  as  if  dead, 
laid  in  any  position,  or  tied  into  a  knot.  The  only  movement  it  persists 
in  making  is  that  of  turning  its  ventral  side  uppermost.  Ant-lions  (Fig. 
203)  are  very  rarely  found  at  the  south  end  of  Lake  Michigan,  except 
in  the  oak  belt.  They  make  cylindrical  conical  pits  in  the  sand  (177, 
179).  The  most  characteristic  species  under  the  bark  of  fallen  oaks  is 
the  flatbug  (Fig.  209). 

b)  The  field  stratum. — This  stratum  is  dominated  by  many  flowering 
plants,  such  as  Monarda,  etc.  The  addition  of  a  host  of  insects  and 
spiders  not  present  in  the  earlier  conditions  is  noticeable.  Of  the  grass- 
hoppers we  add  six  species   {Scudderia  texensis,  Xiphidium  stridum, 

Chloealtis  conspersa , 
Schistocerca  rubigino  s  a , 
Oecanthus  fasciatus,  and 
Conocephaliis  ensiger) 
(40). 

The  andrenid  bees 
{Agapostemon  splendens) 
and  various  robber-flies 
are  numerous.  On  the 
Monarda  the  honey-bees, 
bee-flies  (Fig.  210),  bum- 
blebees, and  spiders  {Mis- 
urnessus  asperatus  [Figs. 
207 ,  208] ,  Dictynafoliacea , 
Agriope  trifasciata,  and 
Epeira  sp.)  are  common. 
The  blueberry  is  com- 
monly one  of  the  small  herbs  of  the  field  stratum  and  upon  it  we  find 
several  characteristic  galls. 

c)  Shrub  stratum. — This  stratum  is  made  up  of  the  choke-cherry, 
young  oaks,  rose,  etc.  The  shrub  which  has  been  given  most  attention 
is  the  choke-cherry.  On  this  the  lacebugs  (Fig.  211)  are  often  numerous; 
the  puss  caterpillar  (Cerura  sp.)  (163)  sometimes  occurs.  This  cater- 
pillar has  a  pair  of  long  projections  at  the  posterior  end.  When  disturbed 
it  extends  and  waves  these  projections  and  thus  makes  of  itself  one  of 
the  most  fantastic  of  our  caterpillars. 

Grapevines  are  not  uncommon  on  the  dunes  and  we  often  find  a 
curious  red  petiole  gall  on  them,  which  is  not  common  elsewhere.  The 
large  fleshy  larvae  of  the  achemon  sphinx  (163)  are  sometimes  taken. 


Fig.  210. — A  bee-fly   {Bomhylius    major   Linn.) 
(from  Williston  after  Lugger) . 


RED-OAK  ASSOCIATION 


233 


d)  Tree  stratum. — The  black  oak  (137)  is  attacked  by  a  large,  light- 
green  larva  which  has  a  narrow  yellow  stripe  down  its  back  {Nadata 
gibbosa).  It  is  also  attacked  by  several  slug  caterpillars  which  we  have 
been  unable  to  identify.  The  beautiful  prominent  larva  with  a  saddle 
of  red  is  occasionally  taken.  Commonly  feeding  on  the  juices  of 
the  leaves  are  several  species  of  leaf-hopper^  (ry/>/?/ocy6a  querci  var. 
bifasciata),  the  common  grapevine  leaf-hopper,  and  the  white  black- 
marked  leaf-hopper  which  occurs  also  on  the  hickory.  The  oak  tree- 
hoppeTf^{Tclemona  querci)  (Fig.  212)  is  a  common  leaf-sucker.  Squirrels 
are  probably  occasional  visitors  as  they  come  to  feed  upon  acorns.  The 
acorns  are  also  often  attacked 
by  weevils. 

In  such  a  set  of  graded 
forest  stages  as  we  are  dis- 
cussing it  is  possible  to  note 
many  stages.  The  stage 
which  we  have  just  de- 
scribed passes  more  or  less 
rapidly  into  the  next,  the 
rate  of  change  depending 
upon  the  height  above 
ground  water  and  the  degree 
to  which  the  sand  is  shifted 
by  the  wind.  On  the  parallel 
ridges,  the  next  and  perhaps 

most  notable  forest  stage  contains  white  oak  and  red  oak  and  is  found 
in  places  on  the  Tolleston,  Calumet,  and  Glenwood  beaches.  The 
ecological  age  of  the  forest  is  determined  by  the  height  above  ground 
water.  Ridge  93,  inside  the  Tolleston  Beach,  is  low  and  forest  has 
progressed  as  far  as  on  the  older  beaches. 


Fig.  211. — The  lacebugs  common  on  the  oak 
and  wild  cherry  in  the  dune  region  (Corythuca 
(iiritata)  (from  Washburn  after  Comstock) : 
a,  adult;  b,  3'oung. 


V.     Mesophytic  Forest  Formation  (115,  170) 

I.      HYALIODES   OR   BLACK   OAK-RED   OAK  ASSOCLATION 

(Station  63,  also  near  stations  27  and  65;  Tables  L,  LIII,  LVI,  LIX)  (115) 

This  is  represented  at  several  points. 

a)  Subterranean-ground  stratum. — In  this  stratum  the  woodchuck 
or  groundhog  is  common  (142).  Earthworms  have  begun  to  appear. 
The  root-borer  Prionus  (155)  and  several  species  of  ants  are  common, 
while  the  numerous  digger-wasps  of  the  earlier  stage  have  largely  dis- 
appeared.    The  depressions  which  contain  water  in  spring  are  typical 


234 


DRV  AND  MESOPHYTIC  FOREST  COMMUNITIES 


forest  temporary  ponds.  Beneath  the  leaves  and  wood  are  snails 
{Zonitoides  arboreus),  millipedes  (Polydesmus  sp.),  and  centipedes  (Lltho- 
blus  sp.),  and  in  dry  weather  Polygyra  Ihyroides  and  multilineata. 
Ground  beetles  and   rove-bsetles  are  common.      One  finds  Cicindela 


Fig.  212. — The  oak  tree-hopper  {Telamona  querci)  (after  Lugger). 

sexgiUtata,  the  green  tiger-beetle,  here  rarely;    it  is  much  commoner  in 
later  stages,  however. 

In  the  decaying  logs  and  stumps  are  darkling  beetles  (156),  numerous 
wireworms  {Elaleridae),  and  myriopods.  Sometimes  fungus-feeding 
beetles    (Diaperis    hydni   and  Eustrophus  tormentosus)  are  present  in 

numbers.  Ants  are  also  often 
abundant.  Carpenter  ants  are 
common.  The  aphid  housing 
ant  (Lasius  umhratus  subsp. 
mixtus  var.  aphidicola)  is  some- 
times abundant.  In  autumn 
certain  galleries  in  the  wood 
are  crowded  with  woolly  aphids 
which  are  the  so-called  "cows" 
which  the  ants  house  for  the 
winter. 

b)  Field  and  shrub  strata. — 
In  moist  weather  the  snails  {Polygyra)  mentioned  above  are  common 
on  Jthe  herbaceous  vegetation,  while  the  tree-frogs  {Hyla  versicolor  and 
pickeringii)  (139)  are  common,  and  spiders  are  numerous. 

c)  Tree  stratum. — -The  oaks  (137)  are  affected  by  many  of  the  same 
species  as  in  the  earlier  stages.     The  tree-frog  is  sometimes  found  in  the 


Fig.  213. — The  oak  plant-bug  (Hyaliodes 
vitripenms)  (from  Washburn  after  Riley): 
a,  young;  b,  adult. 


HICKOR  Y  A  SSOCIA  TION 


235 


trees  and  the  Avalking-stick  {Diapheromera  femoraia)  (40)  is  common. 
One  of  the  most  characteristic  galls  is  the  oak-seed  gall  (A  ndricus  semi- 
nator),  particularly  abundant  on  white  oak  of  this  stage  and  not  common 
later.  Galls  are  very  common  on  the  white  oak.  The  predatory  capsid 
{Hyaliodes  vitripennis)  (Fig.  213)  is  usually  present  on  the  bark  of  the 
oaks,  and  is  often  in  company  with  book-lice  {Psocus).  The  squirrels, 
chipmunks,  and  birds  of  this  association  are  similar  to  those  of  the  next 
stage  and  will  be  discussed  there. 


Fig.  214. — General  view  of  the  white-oak  red-oak  hickory  forest  (Glencoe). 


2.      THE   GREEN   TIGER-BEETLE   OR   WHITE    OAK-RED   OAK-HICKORY 

ASSOCIATION 

(Stations  56,  64,  65;  Tables  LIV,  LXI)  (Fig.  214) 

This  is  the  climax  forest  of  the  savanna  region.  The  gro\'es  are 
largely  made  up  of  it.  Though  somewhat  disturbed  in  localities  where 
studied,  it  presents  some  variations.  Areas  along  the  north  shore  contain 
considerable  basswood.  The  Higginbotham  woods  at  Gaugars  (Fig. 
215)  contain  very  few  hickories  and  many  maples;  this  type  stands  in 
closer  relation  to  flood-plain  and  marsh  forests  than  those  discussed 
later.  The  woods  at  Suman  are  well  invaded  by  beech  and  maple 
seedlings  and  represent  the  latest  stages  of  this  forest.     It  is  thought 


236 


DRV  AND  MESOPHYTIC  FOREST  COMMUNITIES 


best  to  treat  all  phases  together,  simply  mentioning  the  points  of 
difference. 

a)  Subterranean-ground  stratum. — Earthworms,  borers  in  the  roots  of 
trees,  and  cicada  nymphs  are  numerous.  The  wolf,  groundhog,  and 
the  red  fox  {Vulpes  fulvus  Des.)  nest  in  burrows.  The  latter  brings 
forth  from  four  to  nine  pups  in  early  spring. 

Consocies  of  the  under  side  of  leaves  and  wood:  The  camel  cricket 


A  Mesophytic  Forest 

Fig.  215. — General  view  of  the  Higginbotham  woods  near  New  Lenox, 
of  the  flood-plain  oak-hickor}^  type. 


Woods 


iCeuthophilus)  (Fig.  216),  young  cockroaches,  the  short-winged  grouse 
locust  {Tettigidea  pennata  Morse),  and  the  yellow-margined  millipede 
{Fontaria  corrugate)  (Fig.  218)  are  most  characteristic  under  the  leaves. 
The  large  round  millipede  {Spirobolus  marginatus)  (Fig.  217)  is  common. 
Snails  and  slugs  are  numerous,  several  species  (Polygyra  pennsylvanica 
[Fig.  219],  P.  profunda  [Fig.  220],  Zonitoides  arbor eus,  Pyramidula  alter- 
nata  [Fig.  221],  Pyramidula  solitaria  [Fig.  222],  Agriolimax  campestris 


HICKORY  ASSOCIATION 


237 


Circinaria  concava  [Fig.  223])  are  usually  common  and  Polygyra  albolabris 
is  characteristic  of  the  more  mesophytic  parts. 

The  ruffed  grouse,  oven-bird,  and  woodcock  nest  on  the  ground. 
The  timber  rattlesnake  {Crolalus  durissus  Harlan)  formerly  occurred 
in  rocky  situations  (22).  The  four-toed  salamander  {Hemidactylium 
scutalutn  Schl.)  is  found  locally  (22).  The  white-footed  wood-mouse 
(Peromyscus  leucopus  noveboracensis  Fisch.)  builds  a  nest  under  fallen 


216 


>--~-^ 


218'^ 


219       220 


Inhabitants  of  a  Mesophytic  Forest 

Fig.  216. — The  wingless  wood  locustid  {Ceuthophilus);  enlarged. 

Fig.  217. — The  common  millipede  'Spirobolus  marginatus);  natural  size. 

Fig.  218. — Another  millipede  {Fomaria  corrugaf.e);  natural  si/.e. 

Figs.  219-223. — Snails  from  the  woods.  219,  Polygyra  pennsylvaiiica  Green; 
220,  Polygyra  profunda  Say;  221,  Pyramidula  solUaria;  222,  Pyramidiila  alternata; 
223,  Circinaria  concava. 


logs  and  stumps  (21).     The  gray  fox  {Urocyon  cinereoargenteus  Mull.)  is 
more  dependent  upon  heavy  timber  than  the  red  fox  (21).     The  cotton- 
tail (21),  which  belongs  to  forest  edge,  frequently  winters  in  the  woods. 
The  bear  was  formerly  common,  nesting  under  fallen  trees  and  feed- 


238 


DRY  AND  MESOPHYTIC  FOREST  COMMUNITIES 


ing  extensively  on  the  berries.  The  timber  wolf  had  its  den  in  similar 
places,  though  often  burrowing  into  the  ground.  In  Central  Illinois 
moles  are  common  residents  of  groves  near  cultivated  lands.  The 
Virginia  deer  (Odocoileus  virginianus  Bodd.)  was  formerly  common  and 
was  preyed  upon  by  the  wolves  and  panthers.  The  latter  sometimes 
leaped  upon  its  prey  from  the  branches  of  the  trees  (142). 


226  "'3      ^  ' 


Inhabitants  of  Trees  and  Shrubs 

Fig.  224. — The  spiny  spider  (Acrosoma  gracilis),  legs  wanting  (after  Emerton). 

Fig.  225. — Another  spiny  spider  {Acrosoma  spiiiea) :  a,  female;  b,  male;  c,  young 
(after  Emerton.) 

Fig.  226. — Acorn  weevils:  a,  dorsal  view;  b,  side  view  (after  Riley,  U.S.  D.  Agr.). 

Fig.  227. — A  red-oak  sawfly  larv-a. 

Fig.  228. — A  female  walking-stick  on  the  trunk  of  a  tree,  with  a  caterpillar 
(Halisidota  sp.)  on  the  bark  above. 


Consocies  of  logs  (in  wood  and  under  bark) :  There  is  a  regular  suc- 
cession of  forms  which  affect  any  one  species  of  the  trees  of  the  forest. 
The  earlier  forms  usually  attack  the  trees  while  they  are  standing,  and 
accordingly  belong  more  properly  to  the  tree  stratum.     When  the  bark 


HICKORY  ASSOCIATION 


239 


has  become  loosened,  however,  we  find  practically  all  the  small  inverte- 
brates recorded  on  the  ground.  The  small  andrenid  bees  {Augochlora 
pur  a)  build  small  cells  under  the  bank  and  fill  them  with  pollen.  One 
egg  is  laid  in  each  cell  (July),  and  the  larva  feeds  upon  the  pollen. 
Sowbugs  (Cylisticus  convexus  and  Porcellio  rathkei)  and  centipedes 
{LUhobius,  Lysiopetalum  laclarium,  and  Geophilus  rubens)  are  common. 
Numerous  beetles  burrow  into  the  wood  or  feed  on  fungi  under  bark. 
Some  of  the  chief  borers  are  {Cerambycidae)  Prionus  and  Orthosonia 
brunneum,  and  also  Passalus  cornulus.  The  large  slug  {Philomycus 
carolinensis)  is  common. 


Fig.  229.— The  oak  twig  pruner  (Elaphidion  villosum  Fabr.)  (after  Washburn) 
{17th  Rcpt.  Minn.  Agr.  Exp.  Sta.,  p.  165,  Fig.  36). 


b)  Field  stratum. — After  rains  the  slugs  and  snails,  especially  the 
young,  crawl  upon  the  vegetation.  Several  flies  are  common  {Sapromyza 
phlladelphica).  A  leai-ho-ppex^XScaphoideus  auronitens),  a  damsel-bug 
{Reduviolus  annulatus),  the  shield  grasshopper  {Atlanticus  pachymerus) , 
and  a  spider  {Theridium  frondeuni)  have  all  been  recorded. 

c)  Shrub  stratum. — Many  spiders  build  their  nests  and  webs  in  this 
stratum.  Epeira  domicilorum  was  found  with  a  nest  of  leaves  drawn 
together  adjoining  its  web.  Epeira  gigas,  the  large  yellow  spider,  builds 
near  open  places,  on  high  shrubs.  The  web  is  a  large  orb,  the  nest  in  a 
convenient  gxoup  of  leaves  near  the  upper  side. 


240 


DRV  AND  MESOPHYTIC  FOREST  COMMUNITIES 


Acrosoma  gracilis  (Fig.  224)  (138,  172)  commonly  stretches  its  web 
between  the  trunks  of  two  small  trees  which  stand  about  4  ft.  apart. 
The  center  of  the  orb  is  commonly  about  6  ft.  above  the  ground ;  it  is 
nearly  vertical.     The  spider  usually  hangs  near  the  center. 


The  Standing  Bead  Oak  and  Inhabitants 

Fig.  230. — Showing  the  larva,  pupa,  and  adult  of  the  large  wood-eating  beetle 
{Pas.salns  corniitiis)  ]  about  natural  size. 


Acrosoma  spinea  (Fig.  225a,  h,  c)  (138,  172)  commonly  places  its  web 
in  a  nearly  horizontal  position  on  the  upper  side  of  leaves.  The  spider 
clings,  ventral  side  up,  on  the  lower  side  of  the  web.  The  web  is 
usually  from  i  to  3  ft.  from  the  ground.  The  spider  often  falls  to  the 
ground  when  disturbed.  The  two  Acrosomae  are  confined  to  mesophytic 
forests  of  the  oak-hickory  type.  They  have  not  been  recorded  north  of 
Chicago. 


HICKORY  ASSOCIATION 


241 


A  wasp  (Polistes)  builds  its  comb  of  wood  pulp  on  the  under  side  of 
the  leaves.  Various  larvae  and  beetles  feed  upon  the  leaves  of  the 
undergrowth.  A  bug  (Acanthocephala  terminalis),  a  leaf-beetle  (Calli- 
grapha  scdaris),  the  fork-tailed  katydid  (Sciidderia  furcata),  the  round- 
winged  katydid  {Amblycorypha  iihleri  Brun.)  (40),  and  various  other 
insects  have  been  secured  from  shrubs,  especially  in  slight  open- 
ings. The  black  snake  (22)  (now  rare)  often  rests  on  bushes  in  such 
forests.  The  black  and  yellow  warblers  and  woodthrush  nest  on  the 
shrubs. 


The  Standing  De.\d  Oak  and  Inhabitants 

Fig.  231. — The  successor  of  Passalus  {Philomycus  carolinensis). 
Fig.  232. — The  work  of  a  carpenter  ant  in  the  same  tree. 


d)  Tree  stratum. — The  walking-stick  (Fig.  228)  (Diapheromera  femo- 
rata)  (40)  is  common  on  the  tree  trunks  in  the  fall.  The  red  oak 
supports  the  tree  cricket  (Oceanthus  angustipennis),  the  stinkbug 
{Euschistus  tristigimus),  and  the  oak-leaf  beetle  (Xanthoma  lo-notata). 
Felt  records  several  insects  injurious  to  the  red  oak  alone.  From  the 
white  oak  we  have  taken  the  katydid  (Cyrtop/iillus  perspicillatus),  the 
larvae  of  sawflies  (Fig.  227)  and  moths  {Anisota  senatoria),  and  various 
galls.     Several  weevils  (Fig.  226a,  b)  occur  on  acorns,  and  the  twig- 


242 


DRV  AND  MESOPHYTIC  FOREST  COMMUNITIES 


borer  (Elaphidion  villosum)  (Fig.  229)  in  the  twigs.  The  hickory- 
supports  many  larvae,  including  a  Phylloxera  which  forms  galls  on  the 
leaves  (see  Fig.  277,  p.  273). 

The  red-tailed  and  red-shouldered  hawks,  the  red-headed  wood- 
pecker, the  wood-pewee,  the  crow,  bluejay,  robin,  and  bluebird  nest  in 
the  trees.     The  panther  and  wildcat  (Lynx  rufus)  were  former  residents. 


Fig.  233. — The  beech  woods.     Note  small  amount  of  undergrowth. 

Dead  standing  oaks  are  attacked  by  a  series  of  animals.  As  soon 
as  the  wood  begins  to  soften,  the  four-legged  larva  of  Pas  solus  cornutus 
often  appears.     This  is  succeeded  by  slugs  and  ants  (Figs.  230,  231,  232). 

2.      WOOD-FROG   OR   BEECH  AND   MAPLE   FOREST   ASSOCIATION 

(Stations  70,  71,  yia,  716;  Tables  LV,  LXII)  (Fig.  233) 
The  coming  of  this  stage  is  indicated  by  the  presence  of  seedlings 
of  beech  and  maple  in  the  oak-hickory  forest,  e.g.,  at  Suman,  Ind. 


BEECH  ASSOCIA  TION 


243 


a)  Subterranemirground  stratum. — Earthworms  continue;  an  occa- 
sional groundhog  has  been  seen,  though  they  are  probably  much  less 
common  here  than  in  the  preceding  stages.  The  stratum  appears  less 
closely  inhabited  than  the  preceding.  Under  leaves  are  found  scattered 
snails,  centipedes,  etc.  The  yellow-margined  millipede  {Fontaria  cor- 
rugate) is  most  common.  There  is  an  occasional  Centhophilus.  We 
have  found  no  other  Orthoptera  in  beech  woods  proper,  though 
Hancock  records  several  (40,  p.  422).  Animals  are  more  abundant 
under  logs  than  under  leaves.  Here  we  find  the  large  slug  {Philomycus 
carolinensis)  and  several  species  of  snails  which,  though  characteristic, 


d 


236  ^'^^ 


238  239 


Figs.  234-240.— Some  beech  woods  snails:  Ground  stratum;  234,  Pyramidula 
perspectiva;  235,  Polygyra  infleda;  236,  Poly gyr a  palUata;  22,7,  Polygyra  frauduleuta; 
23S,  Polygyra  oppressa;   239,  Pyramidula  solitaria,  adult;    240,  Polygyra  albolabris. 

are  not  abundant.  These  snails  are  Polygyra  infleda  (Fig.  235), 
oppressa  (Fig.  2^8),  frauduleuta  (Fig.  237),  palliata  (Fig.  236),  albolabris 
(Fig.  240),  Pyramidula  solitaria  (Fig.  239),  alternata,  and  perspectiva 
(Fig.  234),  and  Zonitoides  arboreus.  These  species  of  Polygyra  are 
distinguishable  by  the  presence  of  characteristic  "teeth"  in  the 
entrance  of  the  shells.  The  large  spider  (Dolomedes  tenebrosus)  and 
millipede  (Spirobolus  marginatus)  occur.  Crane-fly  larvae,  ground 
beetles  (Plerostichus  adoxus),  a  centipede  (Geophilus  rubens),  the  wood- 
frog  {Rana  syhatica)  (Fig.  241)  (139),  and  the  red-backed  salamander 
{Plethodon  cinereus)  (152)  (Fig.  242)  are  common  and  characteristic. 


244 


DRV  AND  MESOPHYTIC  FOREST  COMMUNITIES 


Pickering's  tree-froo;  is  sometimes  abundant.     The  oven-bird  nests  on 
the  ground. 

b)  Field  and  shrub  strata. — The  field  stratum  is  very  poorly  devel- 
oped in  summer,  herbaceous  plants  being  most  abundant  in  early  spring. 
The  paA\paw  supports  the  zebra  swallowtail  butterfly  (Papilio  ajax 
Linn.),  and  the  spice-bush  the  green-clouded  swallowtail  (Papilio  troilus 
Linn.).  In  the  shrubbery  in  general  we  have  taken  snout-beetles,  leaf- 
beetles,  etc.,  usually  as  incidental  occurrences,  however.  A  lacebug 
(Gargaphia  tiliae),  which  has  been  recorded  on  basswood,  and  several 


Representatives  of  the  Wood -Frog  Associatiox 
Fig.  241. — Thewood-irog  {Rana  syhalica);   about  natural  size. 
Fig.  242. — The  red-backed  salamander  {Plethodon  cinereus);  about  natural  size. 
Fig.  243. — The  remains  of  a  fungus  found  growing  under  a  pile  of  logs  in  moist 

woods  (not  beech),  and  the  fungus-feeding  beetle  (Tritoma   unicolor  Say);    about 

natural  size. 


species  of  bugs  and  beetles  have  also  been  taken,  but  all  are  incidental 
and  of  widely  distributed  species. 

c)  Tree  stratum. — On  trunks,  shelf  fungi  are  common  and  are  usually 
inhabited  on  the  under  side  by  the  tenebrionid  beetle  (Boletotherus 
bifurcus)  (156),  a  curious  rustic  beetle.  Few  characteristic  species  have 
been  taken  from  the  trees.  From  the  bark  of  the  trunk  we  have  taken 
harvestmen  {Oligolophus  pictus  and  Liobunum  nigropalpi)  and  from  the 
t\ngs  woolly  aphids  {Pemphigus  imbricator)  (Fig.  245).  There  is  an 
occasional  lo  larva  on  the  leaves  (Fig.  244). 

The  great  crested  flycatcher,  wood-pewee,  bluejay,  scarlet  tanager, 
red-eyed  vireo,  and  woodthrush  nest  in  the  low  trees  and  on  the  lower 


BEECH  ASSOCIATION 


245 


levels  of  the  higher  trees.  Little  is  known  of  the  mammals  of  the  beech 
and  maple  forest.  Deer,  bears,  wolves,  foxes,  hares,  etc.,  appear  to 
prefer  forests  with  more  undergrowth  and  herbaceous  vegetation. 
Squirrels  are  fond  of  beechnuts,  and  are  jjrobably  the  chief  resident 
mammals.  The  fox  squirrel,  gray  squirrel,  red  squirrel,  and  other  mam- 
mals of  the  preceding  stages  doubtless  occur. 

d)  Consocies  of  the  decay  of  a  beech. — Succession:   Any  tree  which 
is  torn  down  by  the  wind  or  lightning  is  attacked  by  a  series  of  borers, 


Leaf-  and  Twig-Feeders 

Fig.  244. — The  nest  of  an  lo  caterpillar  in  the  beech  leaves;  reduced. 
Fig.  245. — Woolly  aphids  {Pemphigus  imhricator  Fitch)  on  the  twig  of  the  beech; 
reduced . 


etc.,  each  one  helping  to  prepare  the  way  for  those  that  follow.  To 
illustrate  the  general  principles,  the  succession  of  animals  in  any  species 
of  tree  might  be  presented.     We  have  chosen  the  beech. 

According  to  Felt  (137),  living  beeches  are  commonly  attacked  by  the 
red-horned  borer  {Ptilinus  ruficornis  Say)  which  bores  into  the  bark 
and  wood,  and  another  borer  {Anthophilax  attenuatus  Hald.)  which  lays 
eggs  in  the  galleries  thus  formed.  We  have  examined  four  stages  of  the 
decav  of  beech  trees. 


246 


DRY  AND  MESOPHYTIC  FOREST  COMMUNITIES 


First  stage:  Tree  freshly  fallen  (Fig.  246).  Only  forms  recorded  are 
the  apple-tree  engraver  beetle  (Pterocyclon  mali  Fitch)  (Fig.  247)  which 
makes  galleries  in  the  solid  wood. 


Succession  in  the  Beech  Log 

Fig.  246. — The  freshly  fallen  beech. 

Fig.  247. — The  first  borer  to  enter  the  fallen  tree  (Pterocyclon  mali  Fitch); 
greatly  enlarged  (from  Lugger  after  U.S.  Dept.  Agr.). 

Fig.  248. — The  partially  decayed  beech. 

Fig.  249. — Closer  view  of  the  same  showing  the  burrows  of  the  different  wood- 
boring  larvae  in  the  softened  wood. 

Fig.  250. — Shows  the  last  stage  in  the  decay  of  the  beech. 


CAUSES  OF  SUCCESSION  247 

Second  stage  (Fig.  248):  Bark  loosened;  wood  still  solid  or  barely- 
softened.  Under  the  bark  were  the  flattened  Pyrochroidae  larvae,  the 
small  snail  {Zonitoides  arboreus),  a  few  of  the  four-legged  larvae  of 
the  passalid  (Passalus  comutus),  many  larvae  of  fungus-gnats  (Myceto- 
philidae),  and  a  single  specimen  each  of  the  beetle  {Penthe  pimelia)  and 
the  slug  (Philomycus  carolinensis).  None  of  these  were  abundant. 
The  flattened  beetle  larvae  were  most  characteristic. 

Third  stage  (Fig.  249):  The  wood  is  thoroughly  softened  and  the 
bark  generally  loosened.  Here  the  animals  present  in  the  earlier  stage 
are  increased  in  numbers.  The  passalid  larva  is  more  abundant. 
Slugs  are  numerous.  Snails  {Pyramidula  alternata)  are  found  in  such 
situations  as  are  large  enough  for  them  to  enter.  Fungus-eating  beetles 
are  present  {Megalodacne  heros  Say).  A  click-beetle  larva  (Tharops 
ruHcornis  Say)  bores  into  the  softened  wood. 

Fourth  stage  (Fig.  250):  The  bark  fallen  off;  the  log  a  mere  mass  of 
rotten  wood.  Such  a  log  is  only  shelter  for  the  regular  inhabitants  of 
the  forest  floor  which  we  have  already  enumerated  on  the  preceding 
pages. 

VI.     General  Discussion 

A  study  of  the  tables  shows  several  points  of  interest.  Take  first 
the  ground  stratum.  Beetles  which  live  under  decaying  wood  are 
common  on  the  beach  where  the  decaying  wood  is  common,  but  are 
absent  through  the  Cottonwood,  pine,  and  black-oak  stages.  They 
appear  again  with  the  fallen  leaves  and  moist  logs  of  the  black  oak-red 
oak  stage.  Vegetation  in  itself  is  not  directly  important.  Moist 
decaying  wood  is  common,  both  on  the  beach  and  in  the  woods.  Wood 
and  moisture  are  evidently  essential  to  such  animals.  Turning  to  the 
snails,  which  probably  all  come  out  into  the  open  to  feed  during  the  night 
and  during  moist  weather,  we  note  that  they  do  not  appear  until  the 
under-log  beetles  put  in  their  second  appearance.  In  general  the  total 
number  of  species  and  of  individuals  increases  until  the  oak-hickory 
stage  is  reached  and  falls  off  again  in  the  beech  and  maple  stage. 

In  general  we  note  that  as  the  forest  passes  from  the  bare-sand  stage 
to  the  beech-maple  stage,  there  is  a  great  increase  in  the  space  to  be 
inhabited  by  animals  and  the  diversity  of  possible  habitats,  at  least  up 
to  the  oak-hickory  stage. 

I.      CAUSES   OF   SUCCESSION 

The  causes  of  succession  in  forests  are  chiefly  changes  in  physical 
condition  with  increase  in  denseness  of  vegetation,  such  as  the  increase 


248 


DRV  AXD  MESOPHYTIC  FOREST  COMMUNITIES 


of  moisture  of  the  atmosphere,  decreased  light,  decreased  temperature 
maximum  in  summer.  The  poisoning  of  the  soil  by  root  excretions 
and  the  modification  of  conditions  on  the  ground  brought  about  by  a 


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Fig.  251.— Mean  daily  evaporation  rates  (c.c.  per  day)  in  the  ground  stratum  of 
four  of  the  animal  communities  (after  Fuller). 


given  set  of  trees  are  believed  to  prevent  the  germination  of  seeds  of 
most  of  such  trees,  and  at  the  same  time  to  prepare  the  way  for  those  of 


CAUSES  OF  SUCCESSION 


249 


differently  adapted  species.  The  factors  as  expressed  in  terms  of  the 
evaporating  power  of  the  air  are  shown  in  Figs.  251,  252,  and  253,  which 
are  graphic  representations  of  the  results  of  a  season's  study  by  Fuller 
(131).  The  graph  of  the  cottonwood  dunes  is  characterized  by  great 
fluctuations. 

The  graph  for  the  pine  dunes  is  decidedly  lower  and  more  regular  in  its 
contour  than  that  of  the  association  which  it  succeeds.     Its  four  nearly  equal 


0                        10                     20 

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Pine  dune 
Oak  dune 

Oak-hickory  forest 
Beech-maple  forest 

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Fig.  25.3. — Showing  the  comparative  evaporation  rates  (c.c.  per  day)  in  the  ground 
stratum  of  the  different  animal  communities  from  May  to  October  (after  Fuller). 


0                       10                      20                      30 

CottunMTDod  dune 
Pine  dune 
Oak  dune 
Beech-maple  forest 

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Fig.  253. — Showing  the  comparative  evaporation  rates  (c.c.  per  day)  in  four  of  the 
animal  communities  on  the  basis  of  the  maximum  amount  per  da}'  for  any  week  from 
May  to  October  (after  Fuller). 


maxima  would  indicate  that  within  its  limits  there  was,  throughout  the  sum- 
mer season,  a  continuous  stress  rather  than  a  series  of  violent  extremes.  On 
the  whole  it  shows  a  water  demand  of  little  more  than  half  of  that  occurring 
in  the  cottonwood  dunes.  Its  greatest  divergence  is  plainly  due  to  the  ever- 
green character  of  its  vegetation  and  is  seen  on  its  low  range  in  May  and  the 
iirst  part  of  June,  and  again  in  October  when  it  falls  below  that  of  the  oak 
dunes  and  is  even  less  than  that  of  the  beech-maple  forest.  This  would  give 
good  reasons  for  expecting  to  find  within  this  association  truly  mesophytic 
plants  [and  moist  forest  annuals]'  whose  activities  are  limited  to  the  early 
'  The  words  in  brackets  are  added. 


250  DRV  AND  MESOPHYTIC  FOREST  COMMUNITIES 

spring.  Evaporation  in  the  various  associations  varies  directly  with  the  order 
of  their  occurrence  in  the  succession.  The  differences  in  the  rate  of  evapora- 
tion in  the  various  plant  associations  studied  are  sufficient  to  indicate  that 
the  atmospheric  conditions  are  most  efficient  factors  in  causing  succession 
(Fuller,  131). 

A  comparison  of  Fuller's  (131)  data  with  the  tables  or  lists  of  ani- 
mals shows  that  the  distribution  and  succession  of  animals  is  dearly 
correlated  with  the  evaporating  power  of  the  air.  Further  comparison 
with  the  description  of  different  forest  stages  shows  that  the  evaporating 
power  of  the  air  may  be  taken,  in  this  case,  as  an  index  of  the  materials 
for  abode,  etc. 

2.      CHARACTERS   OF   THE   COMMUNITIES 

It  is  possible  to  characterize  the  formations  of  the  forest  in  physio- 
logical terms,  though  these  cannot  be  of  a  very  definite  kind  until  the 
mores  have  been  studied  in  detail,  and  accurate  measurements  made. 
Taking  them  stratum  by  stratum,  we  may  note  the  following  obvious 
characters : 

a)  Pioneer  communities. — The  communities  of  the  cottonwood,  pine, 
and  black-oak  stages  may  be  designated  as  pioneer  because  of  the 
presence  of  bare  mineral  soil. 

Subterranean  and  ground  strata:  (a)  The  cottonwood  community 
is  characterized  by  animals  which  breed  and  spend  the  dark  and  cloudy 
days  chiefly  below  the  surface  of  the  sand.  They  are  very  largely 
diurnal  and  predatory,  and  are  exceedingly  swift  and  wary.  The  bur- 
rowing spider  {Geolycosa  pikei)  is  one  of  the  few  nocturnal  animals. 

(b)  The  pine  community  is  characterized  by  similar  mores,  but  is 
to  be  distinguished  from  the  preceding  by  the  presence  of  many  animals 
which  prefer  sand  that  is  less  shifting  and  which  is  sHghtly  darkened  by 
humus  (170).  Animals  requiring  "cover,"  such  as  the  Hzard,  the  blue 
racer,  a  few  ground  squirrels,  etc.,  give  character  because  of  their  absence 
from  earUer  and  later  communities. 

(c)  The  black-oak  community  represents  the  climax  of  diversity 
of  the  subterranean  and  ground  strata.  The  bare-sand  mores  continue 
in  the  open  spaces,  which  we  have  designated  as  transition  areas.  Leaf- 
cutters  are  now  present,  while  among  the  burrowers  the  root-borers 
(prionids  and  lucanids)  work  on  the  roots  of  the  decaying  trees.  The 
behavior  differences  between  this  and  the  preceding  community  are 
differences  of  detail  which,  for  the  making  of  deductions,  would  require 
much  careful  studv. 


CHARACTERS  OF  COMMUNITIES  251 

Field  and  shrub  strata :  The  field  and  shrub  strata  of  the  Cottonwood, 
pine,  and  oak  communities  are  less  easily  characterized.  The  cotton- 
woods  of  the  beach  are  far  less  commonly  infested  with  aphid  galls  than 
are  trees  of  the  same  species  growing  in  less  exposed  situations.  Further- 
more we  have  never  found  any  of  the  lepidopterous  larvae  such  as 
Basilarchia  archippus  Cram,  near  the  beach.  Animals  living  exposed 
upon  the  trees  are  few  in  number.  The  same  general  conditions  obtain 
on  and  among  the  pines  but  spiders  are  more  numerous.  On  the  black 
oak  the  number  of  phytophagous  animals  is  increased  and  the  number  of 
galls  appears  to  be  greater  than  in  the  later  stages;  the  inhabitants  of 
the  herbaceous  vegetation  are  chiefly  those  found  in  open  situations  such 
as  prairies  and  roadsides,  where  the  physical  conditions  are  similar. 
Some  animals  of  the  same  species  which  make  up  the  black-oak  com- 
munity were  taken  from  a  roadside,  and  after  being  mixed  with  the 
inhabitants  of  the  shrubs  of  the  beech  forest  were  placed  in  a  light  gra- 
dient. Soon  the  insects  and  spiders  of  the  two  communities  separated 
sharply  from  each  other,  the  beech-inhabiting  species  going  to  the  dark- 
est end  while  the  roadside  species  crowded  to  the  light. 

b)  Later  communities. — With  the  coming-in  of  red  oak,  true  forest 
with  the  mineral  soil  largely  covered  with  humus  and  leaves  is  present 
and  very  different  mores  obtain.  The  diurnal  diggers  are  practically 
absent.  Snails,  beetles,  grasshoppers,  spiders,  and  myriopods  living 
under  bark,  decaying  wood,  and  leaves,  avoiding  strong  light  and 
requiring  moisture,  are  the  chief  types.  The  mores  are  typically  forest 
in  character.  The  differences  between  these  and  the  later  stages  are 
those  of  detail  and  degree.  In  general  with  a  lessening  in  the  severity 
of  the  conditions  and  an  increase  in  the  denseness  of  vegetation,  there  is 
a  proportional  increase  in  the  use  of  the  vegetation  as  a  place  of  abode. 
In  the  field  and  shrub  strata,  we  note  that  the  animals  of  the  cotton- 
wood,  pine,  and  oak  stages  are  characteristic  of  open  dry  situations, 
requiring  or  tolerating  strong  light,  while  those  animals  of  the  red-oak, 
hickory,  and  beech  stage  are  negatively  phototactic  to  light  of  the  same 
intensity,  as  shown  by  mixing  the  animals  in  a  gradient. 

The  animals  of  the  tree  strata  frequent  a  limited  number  of  kinds 
of  trees.  Tree  inhabitants  are  few  and  scattered  in  the  Cottonwood 
pme,  and  black-oak  stage  while  animals  inclosed  in  galls  or  cases  are 
common,  if  not  dominant.  In  the  red-oak,  hickory,  and  beech  stage 
phytophagous  animals  are  often  gregarious  and  numerous.  Groups  such 
as  Orthoptera,  beetles,  bees,  and  wasps  are  represented  more  and  more 
by  species  which  make  use  of  the  vegetation  as  forest  development 
goes  on. 


252 


DRY  AXD  MESOPIIYTIC  FOREST  COMMUNITIES 


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ANIMALS  OF  FOREST  SUCCESSION 


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254 


DRV  AND  MESOPHYTIC  FOREST  COMMUNITIES 


TABLE  XLIX.     (Table  L  precedes  Table  XLIX) 

Showing  Forest  Animals  in  the  Early  Stages  of  Forest  Development  of  a 
Clay  Blxiff  of  Lake  Michigan 
Subterranean  and  ground  strata,  i;  bare  clay,  2;  sweet  clover,  3;  shrubs,  golden- 
rod,  etc.,  4;  sapling  stage,  animals  same  as  in  (5)  the  oak-hickory  forest  (Station  56). 


Common  Name 

Tube- weaver 

Lycosid 

Carolina  locust 

Mud-dauber 

Tiger-beetle  larvae 

Sowbugs 

Centipede 

Snail 

Snail 

Snail 

Tiger-beetle  larvae 

Snail 

Slug 

Yellow-margined  millipede 
Centipede 


Scientific  Name 

Agelena  naevia  Wal 

Pardosa  lapidicina  Em 

Dissosteira  Carolina  Linn 

Pelopoeus  cementarius  Dru 

Cicindela  purpurea  limbalis  Klg. .  .  . 

Porcellio  rathkei  Brandt 

Geophilus  sp 

Polygyra  thyroides  Say 

Pyramidula  alternata  Say 

Polygyra  monodon  Rack 

Cicindela  sexguUata  Fbr 

Polygyra  albolabris  Say 

Philomycus  carolinensis  Bosc 

Fonlaria  corrugate  Wood 

Lysiopetalum  lactarium  Say 


I 

2 

3 

4 

* 

* 

* 

* 

* 

* 

* 

* 

* 

* 

F 

C 

A 

* 

* 

* 

* 

* 

* 

* 

* 

* 

* 

* 

* 

* 

* 

* 

* 

* 

* 

* 

* 

* 

ANIMALS  OF  FOREST  SUCCESSION 


255 


ANIMALS  RECORDED  IN  THE  GROUND  AND  SUBTERRANEAN 
STRATA  OF  THE  STAGES  NOTED 

In  Tables  LI-LV,  in  the  third  column  B  indicates  breeding;  F,  feeding;  H, 
hibernating,  on  the  situation  indicated  in  column  4.  Figures  in  column  "Litera- 
ture" refer  to  literature  cited  in  the  special  Bibliography  at  the  end  of  the  book. 
Statements  made  on  the  authority  of  others  are  in  italics;  those  starred  are  by 
A.  B.  Wolcott. 

TABLE  LI 

Pine  Stage  (Stations  57,  58,  59) 


Common  Name 

Scientific  Name 

Literature 

Bee  (Andretiidae) 

Halictus  nelumbonis  Rob ...      B  ? 

181 

Larridae 

Tachytes  texaniis  Cres 

Plesia  interrupla  Say 

Anoplius  marginalns  Say.  .  . 
Coluber  constrictor  Lin.,  Var. 
Citellus  13-lineatus  Mitch.  .  . 
Cardiophorus  cardisce  Say. .  . 
Alaus  fnyops  Fabr 

B 
B 

B? 

173 

Scoliidae 

Ceropalidae 

Blue  racer 

Ground  squirrel 

Beetle  {Elateridae) 

Elaterid  beetle 

In  sand 

u 

On  sand 

Under  pine 

bark 

173 

157 

21 

156 

TABLE  LII 
Black-Oak  Stage  (Stations  57,  59,  60,  61) 


Common  Name 

Scientific  Name 

Literature 

Elateridae 

Lacon  rectangularis  Say 

Langnria  trifasclata  Say .... 
Hippisciis  tuberculatus  Beau. 
Coelioxys  rufitarsus  Smith. .  . 

Odynerus  aiiormis  Say 

Heterodon  platirhinos  Latr .  . 

B 
B 
B 
B 

Under  Opimtia 

u 

In  sand 
Bee  nest 

* 

Erotylidae 

* 

Coral-winged  locust. .  . 

Parasitic  bee 

Eunienidae 

40 

Hog-nosed  snake 

B 

In  sand 

157 

TABLE  LIII 
Black  Oak-Red  Oak  Stage  (Station  63) 


Common  Name 

Scientific  Name 

Literature 

Ant 

Lasiiis  umbratus  mixlus 
aphidicola  Walsh 

Camponotiis  ligniperdus 
noveboracensis  Fitch 

Pterostichus  say  I  Brulle 

Uloma  impressa  Mels 

B 

B 
B 
B 

Log 

Log 
Rotten  log 
Rotten  log 

Ant 

54 

Ground  beetles 

Tenebrionidae 

54 
156 
156 

256 


DRV  AND  MESOPHYTIC  FOREST  COMMUNITIES 


(See  explanation  above  Table  LI) 

TABLE  LIV 

Red  Oak-Hickory  Stage  (Stations  64,  65,  69) 


Common  Name 

Scientific  Name 

Literature 

Green  tiger-beetle .... 
White-faced  hornet . .  . 

Cicittdda  scxguitala  Fabr .  .  . 

Vcspa  maculaia  Lin 

A  ugochlora  piira  Say 

Geotrupcs  splendidiis  Fabr. .  . 
SlaphyUntts  violaceiis  Grav.  . 
Melaiiotus  communis  Gyl.  .  . 

Pall  if  era  dorsalis  Bin 

Eupsalis  minuia  Dru 

B 
H 

In  soil 
Rotten  wood 

179 

Scarabaeidae 

Slaphylinidae 

Elateridae 

B 
B 

B 
B 

Rotten  log 

u 

(1 

Log 
Solid  logs 

156 
156 

Slug 

91 

Brenthid  beetle 

TABLE  LV 
Beech  Stage  (Stations  70,  71,  710,  716) 


Common  Name 

Frog 

Fly  larva 

Salamander.  .  .  . 

Snail 

Snail 

Snail 

Snail 

Snail 

Snail 

Beetle 

Ant 


Scientific  Name 

Rana  sylvaiica  Le  Conte. .  . 
Pachyrhina  ferruginea  Fabr 

Plethodon  cinereus  Gr 

Polygyra  inflecta  Say 

Polygyra  oppressa  Say .... 
Polygyra  fraudulenla  Pil .  .  . 

Polygyra  palliata  Say 

Pyramidula  solilaria  Say.  . 
Pyramidula  perspectiva  Say 
Xylopinus  saperdioides  Oliv 
Aphaenogasler  tennesseensis 
Mayr 


Literature 


F 

B 

BF 
BF 
BF 
BF 
BF 
BF 

? 

B 
B 


Ground 
Under  leaves 

u 

Leaves  and  log 


Under  bark 
Rotten  wood 


139 

91 
91 
91 

156,  137 


ANIMALS  OF  FOREST  SUCCESSION 


257 


TABLE  L\T 

Distribution  of  Animals  Recorded  from  Vegetation  in  More  Than  One  of 
THE  Animal  Communities  of  the  Forest  Stages  Indicated  by  Numbers 
I,  the  Cottonwood  stage;  1-2,  mixed  cottonwood  and  pine  stage;  2,  pine  stage; 
2-3,  mixed  pine  and  oak  stage  and  open  places  in  the  oak  forest;  3,  black-oak  stage, 
in  its  later  phases  white  oaks  occur;  4,  black  oak-red  oak  stage;  5,  stages  containing 
hickory  but  not  beech  and  maple;  6,  beech  and  maple  stage. 


Common  Name 

Scientific  Name 

I 

1-2 

2 

2-3 

3 

? 
* 
* 
* 
* 

4 

s 

6 

(a)  Spider  (Thomisidae) 
lb)  Butterfly 

Philodromus  alaskciisis  Key 
Anthocharis  genittia  Fabr.  . 
Epcira  domiciloriim  Hentz. . 

Lygiis  pralcnsis  Lin 

Diaphcromera  fcmorata  Say 
Misumcssus  aspcratus  Htz. 
Diclyiia  foliacca  Hentz .... 

Epcira  gigas  Leach 

Thcridium  frond  cum  Hentz. 
1  Acanthoccphala  terminal  is 

* 

* 
* 
* 

* 

* 

? 
* 

* 

? 
* 

(c)  Spider  {Epciridae) .  . 

(d)  Dusky  plant-bug .  .  . 

(e)  Phasmidae 

(/)   Spider  (Thomisidae) 
(g)  Spider  (Dictynidac) . 
(h)  Spider  {Epeiridac) .  . 
(i)   Spider  {Thcridiidae) 
( j)   Bug 

* 

* 

F 

F 

* 

* 
* 
* 

C 

* 

* 
* 

* 

* 

* 

* 

F 

* 

{k)  Stinkbug 

(/)    Stinkbug 

(w)Fly 

j       Dall          

] 
i 

* 

Nezara  hilar  is  Say 

Podisiis  macidivcnlris  Say. . 
Sapromyza  philadelphica 
Mac 

* 
* 

* 

1 

The  letters  below  at  the  left  refer  to  the  species  opposite  which  they  stand  in 
Table  LVI  and  the  numbers  refer  to  the  forest  stages  as  at  the  heads  of  the  columns 
of  Tables  L  and  L\T.  The  capitals  have  the  same  meaning  as  in  the  preceding  tables. 
• 

a — from  cottonwoods  and  juniper  (i,  1-2,  3)  (138,  172). 

b — from  Arab  is  I  y  rata  (175). 

c — from  pine  and  herbaceous  vegetation  (B)  (4)  (172). 

d — herbs  (174). 

c — from  the  trunks  of  various  trees. 

f—Monarda  (2-3),  and  black  oak  (3),  maple  (5)  (138,  172). 

g—F  Monarda  (3)  (173). 

/:— from  undergrowth  (4),  and  beech,  (5)  (138,  172). 

i"— from  shrubs  (4),  and  young  beech  (5)  (138,  172). 

/ — shrubs  (4)  and  maple  trunk. 

^— from  red-oak  trunk  (4)  and  beech  trunk  (5)  {Til  ia  .Citrus,  Gossypium  186). 

/ — ?  (4)  and  beech  leaves  (5)  (predaceous,  185). 

m — herbs. 


258 


DRV  AND  MESOPHYTIC  FOREST  COMMUNITIES 


ANIMALS   RECORDED    FROM   THE   FIELD,   SHRUB,   AND    TREE 
STRATA  OF  THE  FOREST  STAGES  NOTED 

In  Tables  LVII-LXII,  in  the  third  column  B  indicates  breeding;  F,  feeding; 
H,  hibernating,  on  the  situation  indicated  in  column  4. 

TABLE  LVII 

Cottonwood  Stage  (Stations  57,  58,  59) 


Common  Name 

Scientific  Name 

Literature 

Chrysomelid  beetle .  . 
Long-horned  borer. .  . 
Gall  aphid 

Disonycha  qiiinquevittata  Say.      BF 

Plectrodera  scalator  Fab BF 

Pemphigus  populicaulls  Fitch.     BF 
Pemphigus  vagabundus  Walsh.     BF 

Willow 
Cottonwood 

a 

it 

156 
156 
188 

Gall  aphid 

188 

TABLE  LVIII 
Pine  Stage  (Stations  57,  58,  59) 


Common  Name 

Scientific  Name 

Literature 

Leaf-beetle 

Nodonota  tristis  Oliv 

Bassareus  lativiitis  Germ .... 
Xysticus  formosus  Banks.  .  .  . 
Dendryphantes  octavus  Hentz . 

Theridium  spirale  Em 

Ips  grandicollis  Eich 

Evetria  comstockiana  Fern.?.. 

F 
F 

BF 
BF 

Herbs 

a 

Juniper 

• 

u 

Pine 

156,137 

Spider  {Thomisidae). . 
Spider  (AUidae) 

Spider  (Theridiidae).. 

Engraver  beetle 

Pitch -moth 

137 
187,138 

173 
138,172 

137 
137 

ANIMALS  OF  FOREST  SUCCESSION 


259 


(See  explanation  above  Table  LVII) 

TABLE  LIX 

Black-Oak  Stage  (Stations  57,  59,  60,  61) 


Common  Name 


Scientific  Name 


Syrphus  fly 

Andrenid 

Spider  {Thomisidac). . 
Spider  (Epeiridac) .  .  . 

Sprinkled  locust 

Grasshopper 

Tree-cricket 

Texas  grasshopper .  .  . 
Conehead  grasshop- 
per   

Meadow  grasshopper 

Stinkbug 

Flower-bug 

Fork-tailed  larvae .  .  . 

*^   Fulgorid 

Flatbug  

Colydiid  beetle 

Prominent  larva 

Prominent  larva 

Tree-hopper 

Coreidae 

Jassid 

Ci  Jassid 


Milesia  virginiotsis  Dru 

Agapostcmoii  splcndciis  Lepel. 
Pliilodroniiis  pcrnix  Black. . .  . 

Argiopc  Irij'asciata  Forsk 

Chloealtis  conspcrsa  Har 

Schistocirai  nibigiitosa  Har.  . 
Occanlhus  jasciatiis  Fitch.  .  .  . 
Scudderia  tcxensis  Scud 

Coitocephahts  oisigcr  Har.  .  .  . 
Xiphidium  slrictum  Scud.  .  .  . 
Eiischistus  variolarius  Pal. .  . . 

Triphlcps  hisidiosus  Say 

Ccrura  sp 

Otioceriis  dcgccrl  Kirby 

Ncuroctciuts  simplex  Uhl 

Ditoma  qiiadrigutlala  Say .... 

Hcterocampa  giitlivilta  Harr. . . 

Nadala  gibhosa  S.  and  A. .... 

Ordemona  querci  Y\X.ch}\monti- 

cola)  

Charicsterus  anleunator  Fabr. . 
Typhlocyba  querci  var.  bifas- 

ciata  G.  and  B 

Phlepsius  irroratus  Say 


F 

F 

F 

F 

F 

F 

BF 
BF 

BF 
BF 
BF 

F 

BF 
BF 
BF 

F 

BF 
BF 

BF 
BF 

BF 
BF 


Herbs 

Primrose 

Herbs 


Cherry 
Oak 


Literature 


177 
137 
137 
40 
40 
40 
40 

40 
40 
174 
185 
186 
185 
185 
137 
137 
138 

185 
185 

185 
i8s 


26o  DRV  AND  MESOPHYTIC  FOREST  COMMUNITIES 

(See  explanation  above  Table  LVII) 

TABLE  LX 

Black  Oak-Red  Oak  Stage  (STATIO^f  63) 


Common  Name 

Scientific  Name 

Literature 

Jumping  spider 

F 
B 

F 
F 

Herbs 

(( 

White  oak 

Tree  trunks 

Cherry 

138 

Gavenna  celer  Htz 

White-oak  gall 

Predaceous  leaf-bug. . 
Scallop-moth  (larvae) 

Andricus  seminator  Harr 

Hyaliodes  vilripennis  Say.  . .  . 
Hydria  undnlala  Lin 

188 

TABLE  LXI 

Red  Oak-Hickory  Stage  (Stations  64,  65,  59) 


Common  Name 

Scientific  Name 

Literature 

Rove-beetle 

Spider  {Clitbionidae) . 

Locustidae 

Spider  {Epeiridae) .  .  . 

Spider  {Epeiridae) .  .  . 

Spider  {Epeiridae) .  .  . 

"OJassid 

Tachinus  pall i pes  Grav 

Anyphaena  conspersa  Key.  .  . 
AUanlicus  pachymerus  Burm. 

Acrosoma  gracilis  Wal 

Acrosoma  spinea  Hentz 

M angora  macidala  Key 

Scaphoideiis  aiironitens  Prov. 

Odonlota  nervosa  Panz 

Reduviolus  aunidatus  Reut. .  . 
Linyphia  phrygiana  Koch. .  .  . 

Cicada  linnei  S.  and  G 

Calligrapha  scalar  is  Lee 

Eiischistiis  tristigmus  Say .... 
Halisidota  sp 

BF 
F 
B 
F 
F 

B 

F 

BF 
BF 
BF 
BF 
BF 

B 

F 

B 

B 

B 

Mushrooms 
Herbs 
Grass 
Shrubs 

u 
u 
u 
li 
u 

Young  maple 

u 
u 

White  oak 
Red  oak 

u 
u 

Maple 

Hickory 

(1 

177 

138 
40 

138 
138 
138 
177 

Beetle 

Bug  {Nabidae) 

Spider  {Liny phi idae) . 
Cicada 

138 
177 

Leaf-beetle 

Stinkbug 

137 

Oakworm    

A  n  isota  senator ia  Sm.  and  Abb. 
Oecanthns  angustipennis  Fitch. 
Cyrtbphyllns  perspicillatiis  L. . 

Xanthonia  lo-notala  Say 

Symmerisla  albijrons  S.  and  A. 
Datana  angusii  G.  and  R  .  .  .  . 
Phylloxera  caryae-caulis  Fitch. 

137 

Tree-cri;ket 

Katydid 

40 

Leaf-beetle 

Prominent  larva 

Prominent  larva 

Aphid 

137 

137 

188,137 

ANIMALS  OF  FOREST  SUCCESSION 


261 


(See  explanation  aboNc  Table  LVH) 

TABLE  LXII 
Beech  Stage  (Stations  70,  71,  71a,  jib) 


Common  Name 


Beetle 

Fungus-beetle 

Cercopidae  (bug) .  . 


i^^Leaf-  hopper . 


Scientific  Name 


Boletobiiis  ductus  Grav. .  . 

^^olctothcnis  hi  fun  US  Fabr. 

Clasloplfni  oblusa  Say. .  .  . 


Gypoiia  octoUneata  Say .... 

Leaf-hopper Qfassus  olitarius  Say 

Ichneumonidae ;   T/ialessa  atrata  Fabr 

Lacewing Chrysopa  rufuilbris  Burm  .  . 

Lacebuj; Cargo phia  tiliac  Walsh .... 

Ichneumonidae Tragus  vulpinus  Cb 

Pentalomidac Banasa  calva  Say 

Lampyrid  beetle Podabrus  basilaris  Say .... 

Lycosidac Wala  mitraia  Hentz 

Theridiidae Notiouella  inter pres  Cam. .  . 

Harve-tman ■  Oligolophus  pictus  Wood. .  . 

Syrphus  fly S pilomyia  longicornis  Loew. 


Mushrooms 

Shelf  fungus 

Hickory,  maple, 

hazel 
Hickorj',  majjle, 
beech 
Maple 
Larvae 
Maple 
Beech 
Larvae 
Beech 
Maple 


Maple  trunk 


Literature 


177 
177,137 


137 

137 
137 

137 
177 

137 
138 
138 
184 


CHAPTER  XIII 

ANIMAL  COMMUNITIES  OF  THICKETS  AND  FOREST  MARGINS 

I.     Introduction 

The  forest  margin  or  forest  edge  is  a  familiar  natural  situation. 
About  Chicago  there  are  groves  of  trees  which  are  probably  exactly  as 
they  were  before  settlement.  The  forest  ends;  the  prairie  begins.  The 
line  between  the  two  is  markedly  a  narrow  border  of  shrubs  and  rank 
weeds,  usually  only  a  few  feet  wide.  In  other  places  the  forest  ends  at 
a  marsh  side,  lake  side,  or  stream  side,  but  almost  always  with  the 
thicket  of  shrubs  and  rank  weeds.  A  remarkably  large  number  of 
animals  belong  to  this  forest  margin.  Some  of  these  have  been  discussed 
in  connection  with  the  margins  of  bodies  of  water  (chap,  x),  and  the 
marsh  forest  (chap.  x).  The  borders  between  forest  and  prairie 
remain  to  be  discussed.  These  will  be  roughly  separated  into  high  and 
low  forest  margin,  depending  upon  height  above  ground- water  level. 
The  relations  of  these  formations  to  the  other  forest  margins  will  be 
indicated  in  the  tables. 

II.    Low  Forest  Margin  Sub-Formations 

(Stations  45,  49;  Table  LXIII)  (Fig.  254) 

Low  forest  margin  is  usually  the  border  between  swamp  forest  and 

low  prairie.     There  was  originally  much  of  this  in  the  Lake  Chicago 

plain.     One  point  of  special  study  is  the  border  of  the  Wolf  Lake  marsh 

forest  (see  p.  189). 

I.       SUBTERRANEAN-GROUND    STRATUM 

The  ground  is  inhabited  by  earthworms  and  cicada  nymphs,  etc. 
No  burrowing  mammals  have  been  recorded,  but  it  is  probable  that 
the  skunk  sometimes  breeds  in  this  stratum. 

The  cricket  (Nemobius  maculatus)  occurs  under  fallen  leaves,  sticks, 
etc.,  with  an  occasional  snail  (Polygyra  monodon).  The  lubberly  locust 
often  deposits  its  eggs  in  the  ground  (40).  Sowbugs  and  forest-floor 
forms  make  up  most  of  the  remaining  species. 

The  northern  yellowthroat,  the  song  sparrow,  and  the  common 
shrew  sometimes  nest  on  the  ground.  The  skunk  is  sometimes  a  feeding 
resident. 

262 


MOIST  FOREST  MARGIN  263 

2.      FIELD   AND   SHRUB    STRATA 

Here  two  zones  may  be  recognized.  While  there  is  no  reason  for 
separating  them  in  the  ground  stratum,  a  rough  separation  is  here 
possible. 

a)  Rank  weeds,  willow,  dogwood,  grape,  etc. 

b)  Prickly  ash  thicket  with  grape  and  young  elms. 

Outside  the  first  is  a  girdle  of  low  prairie  from  which  low  prairie  plants 
and  some  low  prairie  animals  occasionally  invade  the  forest  margin. 

a)  Girdle  of  rank  weeds,  dogwood,  willow,  etc. — In  open,  grassy  places 
the  garden  spiders  {Argiope  aurantia  and  trifasciata)  (Fig.  255)  fasten 


Fig.  254. — Low  forest  margin  at  Wolf  Lake.  Ind.  In  front  of  a,  low  prairie 
area;  opposite  b,  belt  of  rank  weeds:  opposite  c,  low  shrubs;  opposite </,  high  shrubs; 
opposite  e,  trees. 

their  webs  to  any  firm  support,  such  as  a  young  shrub.  Various  grass- 
hoppers occur  in  open  situations  {Xiphidium  fasciatum  and  brevipenne 
belong  more  properly  to  low  prairie)  (Fig.  256).  The  long-bodied  spider 
{Tetragnatha  laboriosa)  (138)  is  a  common  resident.  On  the  grasses 
beneath  the  shrubs  the  black-sided  grasshopper  {Xiphidium  nigropleura) 
is  abundant.  The  snail  (Fig.  257)  (Succinea  ovalis)  is  sometimes 
common. 

Of  the  bugs  which  frequent  the  blossoms  of  the  coarse  weeds  are  the 
long-legged  bug  (Neides  muticus),  the  buffalo  tree-hopper  (Fig.  259),  and 
the  candlehead  {Scolops  sulcipes)  (Fig.  258).  These  two  and  especially 
the  latter,  with  its  curiously  prolonged  prothorax,  are  the  most  char- 
acteristic.    The  common  plant-bug  (Lygus  pratensis)  (Fig.  261)  and  an 


264 


THICKET  COMMUNITIES 


occasional  dusky  leaf-bug  (Adelphochoris  rapidus)  (Fig.  262)  are  also 
found.  The  large  stinkbugs  {Euschistus  tristignius  a.nd  Jiss His  Uhl.)  are 
common.  They  may  be  predatory  in  the  adult  stage.  The  predatory 
ambush-bug  (Phymata  erosa  fasciata)  lies  in  wait  for  its  pre\'  in  the 


Fig.  255. — The  garden  spider   {Argiope   aiinuilia)  on  its  web;    about  one-half 
natural  size. 


Fig.  256. — The  slender  meadow  grasshopper  (A' //)///(//»w/(;i(/i2/7(;H)  (after  Lugger). 

blossoms.  A  crab  spider  (Mesumena  valia)  and  a  jumping  spider 
(P/iidippus  audax)  are  common  in  the  blossoms  (40,  p  182.)  Various 
lepidopterous  larvae  feed  upon  the  rank  weeds  also. 

On  weeds  and  blossoms  grasshoppers  are  numerous;  we  find  the  Ne- 
braska conehead  {Conocephalus  nebrascensis)  (see  Fig.  260),  the  lubberly 


MOIST  FOREST  MARGIN 


265 


Fig.  257. — The  forest-margin  snail  {Siicciiiea  avails);  twice  natural  size  (after 
Baker). 

Fig.  258. — The  candle-headed  bug  (Scolops  sulci  pes);  5  times  natural  size 
(original) . 

Fig.  259. — The  buffalo  tree-hopper  (Cercsa  bubalns);  5  times  natural  size  (after 
Marlatt,  U.S.  Dept.  Agr.). 

Fig.  260. — The  large  cone-headed  grasshopper  {Conocephalus  robuslus)  (after 
Beutenmiiller  [Am.  Mus.]  from  Blatchley). 


266 


THICKET  COMMUNITIES 


locust  (iMelanoplus  differentialis),  an  occasional  red-legged  locust,  and  the 
striped  shrub  cricket,  the  short-winged  brown  locust  (Stenobothrus  cur- 
tipennis),  the  short-winged  meadow  grasshopper  {Xiphidium  brevipenne), 
and  the  Texas  katydid  {Scudderia  texensis)  (40,  pp.  330,  390). 

The  jug-making  wasp  (Eumenes  fraternus)  (40,  p.  207)  makes  its 
jug-like  nest  on  the  herbaceous  plants.  The  social  wasp  (Polistes)  is 
a  frequent  visitor  of  the  flowers, 
and  sometimes  attaches  its  comb 
to  the  willow.  The  oblong  leaf- 
winged  katydid  (Amblycorypha 
oblongifolia)  (Fig.  263)  (40,  p. 
391)  and  the  fork-tailed  katydid 


262 

Fig.  261. — The  tarnished  plant-bug  {Lygus  prateiisis);  about  one-fourth  of  an 
inch  long  (after  Forbes). 

Fig.  262.— The  dusky  leaf-bug  {Adelphocoris  rapidus);  about  one-fourth  of  an 
inch  long  (after  Forbes). 

{Scudderia  furcata)  (Fig.  264)  are  residents.  The  latter  places  its  egg 
on  leaves  of  shrubs  (40).  Willow  leaf-feeders  are  numerous;  several 
lepidopterous  larvae  are  common.  These  include  the  brilliant  larva  of 
the  smeared  dagger-moth  (Fig.  265),  the  cecropia  moth,  the  willow 
sphinx,  the  viceroy  and  mourning-cloak  butterflies,  the  maia  moth 
(Fig.  266),  the  fork- tailed  caterpillar  (137),  larva  of  the  maia  moth, 
and  others.     The  small  fly  {Bibio  albipennis)  visits  the  flowers  of  the 


MOIST  FOREST  MARGIN 


267 


willow  in  spring  (Fig.  267).  Sawfly  larvae  are  common;  the  large  light- 
colored  one  {Cimbex  americana)  (179)  has  habits  of  special  interest.  The 
female,  which  is  a  wasp-like  insect,  deposits  her  eggs  on  the  under  sides 

of  leaves.    Blisters  are  formed,  and  a 
young  larva  lives  for  a  time  in  each 


263 


264 


Fig.  263.— The  oblong  leaf-winged  katydid  {Amblycorypha  oblongifolia);    (after 
Forbes)  natural  size. 

Fig.  264.— The    fork-tailed    katydid    (Sciiddcn'a  fiircala)    (after   Lugger    from 
Forbes) ;  natural  size. 

of  these.     Later  it  is  to  be  found  living  freely  on  the  leaves.     It  usuallv 

rests  with  the  posterior  segments  wrapped  around  a  petiole  or  twig. 

Pupation  takes  place  in  a 

silken  case.     The  spotted 

sawfiy   larva    (Pteronus 

ventralis  Say)  (179)  is  less 

common. 

Beetles  are  common 
on  the  willow.  The  leaves 
are  eaten  by  May-beetles 
(189)  and  several  leaf- feed- 
ers iCalligrapha  and  Lina 
are  common).  Several 
borers  attack  the  twigs 
{Saperda  concolor) .  Galls 
are  very  numerous.  The 
trunks  of  small  willows  are 
commonly  attacked  by  the 
larvae  of  the  introduced 
snout-beetle  {Cryptorhyn- 
chus  lapathi),  and  the 
goat-moth  larva  {Prionoxystus  robiniae  Feck.),  which  bores  in  the  heart- 
wood.     The  sap  which  exudes  attracts  many  sap-beetles  {Nitidulidae). 


Fig.  265. — The  adult  and  larva  of  the  smeared 
dagger-moth  {Acronyda  oblinita),  which  feeds  upon 
various  forest-margin  weeds  and  shrubs;  natural 
size  (after  Riley). 


268 


THICKET  COMMUNITIES 


The  dogwood  is  fed  upon  by  a  few  larvae.     The  unicorn  larva 

{Schizura  sp.)  is  occasionally  found;    the  young  of    the  spittle  insect 

^   {Aphrophora  4-notala)  are  common.     The  grape  and  Virginia  creeper  are 

attacked  by   several    sphinx    larvae.     The  grapevine   hog   caterpillar 

(Ampelophagus  myron  Cram.)  has  been  taken  from  the  former. 

Nesting  in  the  shrubs  are  the  goldfinch  (more  often  in  trees),  the 
indigo  bunting,  the  northern    yellowthroat,   the  brown    thrasher,  and 

catbird,  all  of  which  feed  in  the 
low  prairie.  The  song  sparrow 
nests  near  the  ground. 

b)  The  bell  of  prickly  ash. — 
This  has  not  been  so  thoroughly 
studied.  The  subterranean  and 
ground  strata  are  similar  to 
those  of  the  forest  adjoining  (see 


266 


267 


Fig.  266. — The  larva  of  the  maia  moth  {Ilemilciica  maia)  which  feeds  on  the 
willow;  natural  size  (from  Lugger  after  Riley,  Div.  Ent..  U.S.  Dept.  Agr.). 

Fig.  267. — Bibio  albipcniiis.  Early  spring  on  the  flowers  of  the  willow.  Breeds 
in  the  ground  (from  Williston  after  Washburn). 

p.  269);  the  ground  and  field  strata  have  some  of  the  same  residents. 
The  adult  Cresphontes  butterfly  {Papilio  cresphontes)  is  common  about 
the  Wolf  Lake  forest  edge  and  Hancock  (40)  has  recorded  the  larva  on 
prickly  ash,  one  of  its  regular  food  plants.  He  also  records  the  true  tree- 
cricket  {Apithes  agitator  Uhl.)  as  inhabiting  prickly  ash  thickets. 


III.    High  Forest  Margin  Sub-Formations 

(Station  48;  Table  LXIV) 

This  surrounds  the  oak-hickory,  black-oak,  and  beech  forests  on  high 

ground.     The  witchhazel,  hawthorn,  sumac,  and  grape  are  the  dominant 

shrubs;  goldenrod,  asters,  and  sunflowers  are  the  chief  herbaceous  plants. 


DRV  FOREST  MARGIN  269 

I.      SUBTERRANEAN-GROUND   STRATUM 

Certain  earthworms,  cicada  nymphs,  and  root-eating  grubs  belong 
here.  This  is  the  regular  breeding-place  of  the  skunk  {Mephitis  meso- 
melas  avia  Bang).  According  to  Seton  (143)  they  go  in  droves  of  six  or 
eight,  and  as  many  as  fifteen  sometimes  occur  in  a  winter  den.  Accord- 
ing to  Seton  its  food  consists  of  various  insects,  grasshoppers,  crickets, 
meadow  mice,  snakes,  and  crayfishes.  The  short-tailed  shrew  in  primeve  1 
conditions  breeds  chiefly  in  such  tangles  of  bushes.  It  digs  in  moss 
and  fallen  leaves  and  loamy  soil,  and  follows  mouse  galleries.  According 
to  Wood  (21)  it  eats  many  mice.  Seton  (143)  states  it  feeds  on  isopods, 
earthworms,  etc.     Its  enemies  are  hawks,  lynxes,  and  weasels. 

Franklin's  ground  squirrel  (Citelliis  Jranklini  Sab.)  burrows  into  the 
ground  deeper  than  the  ground  squirrel  of  the  prairies,  but  is  otherwise 
similar  in  habits.  It  is  gregarious  and  stores  grain  for  winter.  The 
chipmunk  (Taniias  strialus  griseus  Mear.)  is  a  typical  forest  margin 
animal.  It  nests  in  the  ground,  as  a  rule  in  burrows  about  6  to  10  ft. 
long  and  running  diagonally  down  to  a  depth  of  2  to  3  ft.  (21).  It  stores 
nuts  for  winter.  The  jumping  mouse  [Zapiis  hudsonius  Zim.)  is  one  of 
the  most  characteristic  residents;  it  moves  by  great  leaps  and  steers  its 
flight  with  its  tail.  The  woodchuck  should  probably  be  counted  here, 
though  it  belongs  deeper  in  the  forest  than  any  of  the  others.  The  weasel 
is  common  in  this  situation,  though  it  is  perhaps  more  abundant  along 
streams  (Wood). 

The  ground  stratum  supports  many  of  the  small  animals  of  the 
adjoining  forest,  such  as  centipedes,  camel  crickets,  etc.  The  cottontail 
is  one  of  the  chief  residents,  as  it  usually  breeds  in  such  situations.  The 
common  shrew  {Sorex  personatus  St.  Hil.)  (21)  breeds  on  the  ground,  in 
stumps,  etc.  All  of  the  mammals  recorded  in  the  preceding  stratum 
feed  here  when  suitable  food  is  present.  A  considerable  number  of 
mammals  commonly  regarded  as  belonging  to  the  forest  are  said  to  prefer 
thickets.  The  Virginia  deer  is  one  of  these.  It  is  probable  that  the  elk 
was  somewhat  similar  in  habits. 

The  bobwhite  and  mourning  dove  (occasionally)  breed  in  these  situ- 
ations, the  former  often  falling  a  victim  to  the  weasel  (Wood).  The 
high  forest  margin  was  probably  a  favorite  location  for  the  huts  of  the 
aborigines.  Some  of  the  early  travelers  record  huts  around  the  edges  of 
the  prairies.  Such  locations  would  supply  shelter  and  firewood,  etc.,  as 
well  as  sunshine. 

2.      FIELD  AND   SHRUB    STR.A.TA 

Here  the  ground-cherry,  milkweed,  and  thistle  have  a  characteristic 
fauna.     On  the  milkweed  are  the  larvae  of  the  monarch  butterflv,  the 


270 


THICKET  COMMUNITIES 


milkweed  beetle  (Tetraopes  tetraophthalmus  Forst.)  (40,  p.  136),  and  the 
leaf-beetle  {Doryphora  cUvicollis) ;  the  latter  is  very  characteristic.  The 
milkweed  flowers  attract  hosts  of  flies  which  are  preyed  upon  by  vari- 
ous digger-wasps;    bees  are  numerous,  gathering  honey.     The  ground- 


268 


269 


Fig.  268. — The  four-lined  leaf-bug  {Poecilocapsits  liiicatus);  a,  adult;  b,  c,  imma- 
ture forms;  55  times  natural  size  (from  Lugger). 

Fig.  269. — A  long-legged  fly  (Psilopodinns  siplto  Say);  enlarged  (from  Williston 
after  Lugger) . 


270 

Fig.  270. — A  large  robber-fly  {Dasyllis  sp.);  natural  size  (from  Williston  after 
Kellogg). 

Fig.  271. — A  syrphus  fly  {En'stalis  ioiax);  15  times  natural  size  (from  Williston 
after  Kellogg). 

cherry  is  the  food  plant  of  the  "Spanish  fly"  (Epicuaia)  and  the 
Colorado  potato-beetle.  On  the  thistle  we  find  the  larvae  of  the  cos- 
mopolitan and  painted-lady  butterflies  (Pyrameis  huntera  Fab.  and 
cardui   Lin.).      One   of   the   most   characteristic   bugs   is   the    4-lined 


DRV  FOREST  MARGIN 


271 


272 


273 


Fig.  272. — A  leptid  fly  {Cooiomyia  fernigiiica);  enlarged  (after  Williston). 

Fig.  273. — A  large  syrphus  fly  (Milesin  virgiiiiciisis);   enlarged  (after  Williston). 


272 


THICKET  COMMUNITIES 


leaf-bug  {Poecilocapsus  lineatus)  (Fig.  268).  The  long-legged  fly 
(Fig.  269),  the  large  robber-fly  (Fig.  270),  the  common  syrphus  fly 
{Erislalis  tenax)  (Fig.  271),  a  leptid  fly  (Fig.  272),  and  Miles ia  virginien- 
sis  (Fig.  273)  visit  the  flowers  in  numbers.  The  garden  spider  occurs; 
also  high  in  the  shrubs  is  the  brilliant  Epeira  gigas  found  also  in  the 
forest  openings.  The  goldenrod  gall-forming  fly  {Straussia  longipennis) 
(Fig.   274)  with  its  beautifully  marked  wings  is  common.     Professor 


275 


276 


Fig.  274. — The  goldenrod  gall-fly  {Slraussi  longipennis);  much  enlarged  (from 
Williston  after  Kellogg). 

Fig.  275. — One  of  the  crane-flies  {Helobia  hybrida) ;  enlarged  (from  Williston  after 
Lugger). 

Fig.  276. — The  tree-cricket  {Oecanthus  fasciatus);  twice  natural  size  (after 
Lugger). 


Williston  states  that  the  crane-fly  (Helobria  hybrida)  (190)  (Fig.  275) 
occurs.     Several  leaf-bugs  occur;    the  dusky  leaf-bug  is  common. 

Several  species  of  Orthoptera  are  characteristic.  Of  the  tree-crickets 
several  occur  among  which  are  Oecanthus  nivens  DeG.  and  angustipennis 
Fitch  and  fasciatus  (Fig.  276).  Two  or  three  katydids  occur;  the 
round-winged  {Amblycorypha  rotundifolia  Scud.)  is  most  characteristic. 


DRV  FOREST  MARGIN 


273 


The  grape  often  grows  in  these  situations,  and  is  especially  subject  to 
attack  by  the  Phylloxera  (Fig.  277)  and  the  grapevine  June  beetle,  the 
larvae  of  the  8-spotted  forester  {Alypia  octomaculata  Fabr.),  and  the 
grapevine  epimens  {Psychomorpha  eplmensis  Drury)  (163).  All  of  these 
spend  a  part  of  their  lives  in  the  ground.  The  Phylloxera  (Fig.  277) 
winters  on  the  roots  of  the  grape.  The  grape-beetle  larva  bores  in  wood. 
The  pupae  of  the  two  moths  bore  into  rotten  wood  or  the  ground  for 
pupation  and  also  to  spend  the  winter.  This  may  be  an  important  cause 
for  their  presence  in  the  forest  margin.  <^Brownie-bugs  are  common 
(Fig.  278). 


Fig.  277. — The  grapevine  Phylloxera  {Phylloxera  vastalrix  Planch.) :  a,  leaf  galls; 
6,  section  of  gall  with  mother  louse  at  center  with  young  clustered  about;  c,  egg; 
d,  nymph;  e.  adult  female;  /,  same  from  side;  a,  natural  size,  others  much  enlarged 
(after  Marlatt,  Div.  Ent..  U.S.  Dept.  Agr.). 


One  of  the  most  interesting  forms  found  here  is  Mantispa  hrunnea 
(Fig.  279).  This  is  a  neuropterous  insect  with  forelegs  adapted  for 
seizing  prey.  Its  larva  is  a  parasite  in  the  egg-cases  of  spiders.  The 
adult  appears  in  July.  In  the  autumn,  after  the  leaves  have  fallen,  one 
sees  many  nests  of  spiders  on  the  high  forest  margin  shrubs,  so  the  young 
parasites  have  a  good  chance  to  secure  their  best  food  conditions  here. 

Hawthorns  often  occur,  and  on  the  trunks  we  find  woolly  plant-lice 
(Schizoneura)  in  great  white  clusters  (150).  The  hawthorn  supports 
many  of  the  pests  of  the  apple. 


74 


THICKET  COMMUNITIES 


The  birds  of  the  high  forest  margin  are  numerous  (191).  The  gold- 
finch builds  a  nest  of  thistledown,  grasses,  etc.,  on  shrubs  or  low  trees. 
The  chipping-sparrow  builds  its  nest  of  rootlets  and  lines  it  with  horse- 
hair. The  Baltimore  and  orchard  orioles  build  elaborate  nests  on  the 
shrubs  and  feed  in  the  open.  The  field  sparrow  sometimes  builds 
on  the  rank  weeds,  in  other  cases  on  shrubs  near  the  ground.  The 
mourning  dove,  the  indigo  bunting,  and  the  yellow  warbler  nest  on 
shrubs;  the  latter  often  builds  near  water.  The  redstart  builds  in  the 
forks  of  bushes  and  trees.  The  loggerhead  shrike  is  common.  The 
sparrow-hawk  nests  in  deserted  woodpecker  holes  near  the  edge  of  the 
woods  and  feeds  in  the  meadow  or  prairie.     The  flicker  is  similar  in 


278 

Fig.  278. — A  brownie-bug  {Enc/ieiiopa 
binotata  Say) ;  enlarged  (after  Lintner) . 

Fig.  279. — One  of  the  Mantis-like 
neuroptera  {Mantispa  hrunnea);  enlarged. 

habits,  but  uses  holes  of  its  own  making.  The  bronzed  grackle  and 
sharp-shinned  hawk  nest  in  trees  near  the  forest  edge  and  feed  in  the 
prairie.  The  cowbird,  which  lays  its  eggs  in  the  nests  of  other  birds, 
often  chooses  those  nests  of  the  high  forest  margin. 


IV.     General  Discussion 

The  forest  margin,  as  we  have  seen,  possesses  in  addition  to  the  char- 
acteristic species  a  considerable  number  of  species  which  frequent  the 
prairie  or  forest;  our  list  includes  the  breeding  species.  The  classifica- 
tion below  shows  the  various  types  of  habit  in  birds  and  mammals. 

Forest  Margin  Birds  and  Mammals 
(Compiled  from  literature  cited) 
H  indicates  high  forest  margin;  L,  low  forest  margin. 
A.     Breeding  in  the  ground  under  the  shrubs;    feeding  in  the  meadows  or 
prairies  and  woods. 

1.  Mammals:   Skunk  {H),  Chipmunk  {H),  Franklin  ground  squirrel  {H), 
Jumping  mouse  (//).     Feed  chiefly  in  woods. 

2.  Birds:  No  birds  have  this  habit. 


THICKET  ANIMALS 


75 


B.  Breeding  on  the  ground  among  the  shrubs  and  feeding  in  the  open  meadows 
or  prairies. 

1.  Mammals:   Common  shrew  {Sorcx  personatus)  (L),  the  cottontail  (H). 

2.  Birds:  Bob  white  {H),  mourning  dove  {H)  sometimes,  northern  yellow- 
throat  (Z,)  sometimes,  song  sparrow  (Z,)  sometimes. 

C.  Breeding  on  the  shrubs  and  feeding  in  the  forest  edge  and  sometimes  in 
the  open  meadows  or  prairies. 

1.  Mammals:  None. 

2.  Birds:  (o)  Low  forest  margin:  song  sparrow,  goldfinch,  indigo  bunting, 
northern  yellowthroat,  brown  thrasher,  and  catbird. 

{b)  High  forest  margin:  goldfinch,  lark  sparrow,  chipping-sparrow, 
field  sparrow,  indigo  bunting,  yellow  warbler,  redstart,  loggerhead 
shrike,  mourning  dove,  catbird,  cowbird,  Baltimore  oriole,  bronzed 
grackle,  brown  thrasher. 

D.  Breeding  in  the  trees  of  the  forest  and  feeding  in  the  prairies. 

1.  Mammals:    raccoon. 

2.  Birds:    Sparrow-hawk,  sharp-shinned  hawk,  and  several  other  hawks, 
flicker,  bronzed  grackle. 

The  list  shows  animals  which  breed  in  the  margin  of  woods  and  often 
feed  not  only  there  but  in  the  prairies.  Similar  relations  were  noted  by 
Bates  in  the  savannas  along  the  middle  Amazons.  The  advantage  of  the 
forest  margin  lies  in  the  facts  of:  (i)  shade  for  the  nocturnal  and  crepus- 
cular forms;  (2)  abundant  space  in  the  thickets  for  nests;  (3)  large  stiff 
plants  which  accommodate  the  large  animals:  (a)  places  for  the  spiders  to 
stretch  their  nets;  {b)  plants  large  enough  for  the  roosting-  and  nesting- 
places  of  birds  and  larger  insects;  (4)  protection  from  wind  and  from 
winter  freezing  afforded  by  the  forest.  From  the  standpoint  of  food 
relations  many  forest  margin  animals  must  be  counted  in  with  the 
prairie  forms. 

One  of  the  most  striking  facts  concerning  the  forest  margin  animals 
is  (a)  their  wide  distribution  and  {b)  their  survival  under  agricultural 
conditions.  Many  animals  of  importance  as  crop  pests  belong  to  forest 
edges  rather  than  to  the  forest  proper.  They  take  possession  of  the  road- 
sides when  the  country  is  cleared.  Their  distribution  is  a  function  of 
the  forest  margin  type  of  habitat.  While  it  is  a  characteristic  feature 
of  the  forest  border  area,  it  is  also  to  be  found  extending  along  the 
wooded  streams  into  the  great  plains  and  toward  the  east  through  the 
forest  area,  as  the  shrubby  bluff,  the  creek  and  river  margin,  the  tired 
area,  and  the  marsh  margin.  While  local  and  always  leading  a  precari- 
ous existence  in  unstable  situations,  this  type  of  community,  probably 


276 


THICKET  COMMUNITIES 


by  virtue  of  its  adaptation  to  such  conditions,  has  given  us  a  very  large 
number  of  animals  of  very  considerable  economic  importance.  Tables 
LXIII  and  LXIV  indicate  the  forms  which  we  have  found  common  to 
the  forest  margins  and  other  situations. 


TABLE  LXIII 

Animals  Recorded  for  a  Moist  Low-Ground  Forest  Margin  or  Thicket  Near 
Wolf  Lake  (Station  45) 
The  names  that  are  starred  represent  animals  that  have  been  recorded  from  the 
shrubs  and  weeds  along  the  margins  of  bogs,  lakes,  ponds,  and  streams,  June  15  to 
August  30. 


Common  Name 


Orb-weaving  spider 

Jumping  spider 

*Garden  spider 

*Long-bodied  spider 

*Orb-weaving  spider 

*Orb-weaving  spider 

Black-sided  locust 

Tree-cricket 

Fork-tailed  katydid 

Nebraska  conehead 

*Robust  lubberly  locust .  . 
*Red-legged  grasshopper .  . 

*Grasshopper 

*Oblong- winged  katydid .  . 

Long-horned  grasshopper 

Coreid 

Candlehead 

Stinkbug 

*Four-lined  leaf-bug 

Coreid 

Sohtary  wasp 

*Bufifalo  tree-hopper 

Long-legged  bug 

*Ambush-bug 

*Plant-bug 

*Tarnished  plant-bug .  .  .  . 

Flower  ground  beetle .  .  . 
*WiIlow-beetle 

Willow-borer 

Elm-borer 

Introduced  beetle 

*Goldenrod  beetle 

Fork-tailed  larva 

*Wasp 

*Jug-making  wasp 

*Sawfly 

Swallowtail 

*Maia  larva 


Scientific  Name 


Singa  variabilis  Em. 

Attus  palustris  Peck. 

Argiopc  aurantia  Lucas 

Tetragnatha  laboriosa  Htz. 

Epeira  trivitlata  Key 

Epcira  trifoUum  Htz.  (rare) 

Xiphidium  nigropleura  Bruner 

Oecanthus  fasciatus  Fitch 

Scudderia  furcata  Bruner 

Conocephalus  nehrascensis  Bruner 

Melanoplus  dijferentialis  Thos. 

Melanoplus  femttr^ubrmn  DeG. 

Melanoplus  biviltaltis  Say 

Amhlycorypha  oblongifolia  DeG. 

Orchdimitm  indianeiise  Blatch. 

Proknor  beljragei  Hagl. 

Scolops  sulcipes  Say 

Euschistus  fissilis  Uhl. 

Poecilocapsus  linealtis  Fab. 

Corynocoris  disHnctus  Dal. 

Odynerus  iigris  Sauss 

Ceresa  bubalus  Fab. 

Neides  muticus  Say 

Phymata  erosa  fasciala  Gray 

Adelphocoris  rapidus  Say 

Lygus  pratensis  Linn. 

C  alii  da  punctata  Lee. 

Lina  scripta  Fab. 

Saperda  concolor  Lee. 

Sapcrda  lateralis  Fab. 

Cryptorhynchus  lapathi  Linn. 

Trirhabda  tormcntosa  canadensis  Kirby 

Cerura  sp. 

Polistes  variatus  Cress. 

Eutnenes  fraternus  Say 

Cimbex  americana  Leach. 

Papilio  cres phonies  Cram. 

Hemileuca  maia  Dru. 


THICKET  ANIMALS 


277 


«  TABLE  LXIV 

AxiMALS  Recorded  from  the  Medium  Moist  or  Climatic  Forest  Edge  or 
Thicbcet  at  Riverside,  III.  (Station  48) 
Those  starred  have  been  taken  from  weedy  and  shrubby  roadsides  and  identified 
by  specialists.     According  to  the  author's  field  identification  nearly  all  should  be 
starred. 


Common  Name 


Scientific  Name 


Crab-spider 

Jumping  spider .  .  .  . 

Spider 

Spider  (Diclynidae) . 
*Orb-weaving  spider . 

Spider 

Spider 

Texas  grasshopper . 


Runcinia  alealoria  Htz 

Maevia  niger  Htz 

Pisaurina  undata  Htz 

Diclyna  foliacea  Htz 

Epeira  trifolium  Htz 

Alypus  milbcrli  Walck 

Clubiona  obcsa  Htz 

Scudderia  texensis  S.  and  P. . 

Spittle  insect .6  Clastoptera  proteiis  Fitch 

Leaf-hopper il Diedroccphala  coccinea  Forst. 


Four-lined  leaf -bug 

Leaf-bug 

Leaf-bug 

Stinkbug 

Long-horned  beetle 

Long-homed  beetle 

Tortoise  beetle 

Tortoise  beetle 

*01d-fashioned  potato-beetle 
*Goldenrod  bhster  beetle .  . . 

Dock  curculio 

Leaf-beetle 

Beetle  (Erolylidae) 

Beetle  {Erolylidae) 

*Beetle 

*Grapevine  beetle 

*Milkweed  leaf -beetle 

Ground  beetle 

Oak -pruning  twig-borer .  .  .  . 

Flower  beetle  {Carabidae) .  . 

Lantern-fly 

Wasp 

Bee  {Halict'idae) 

Crane-fly 

Crane-fly 

Fly 

Goldenrod  gall  fly 


Poecilocapsus  lineatus  Fab . 

Stiphrosoma  slygica  Say 

Ilnacora  stalii  Reut 

Podisus  macuUventris  Say 

Oberea  tri punctata  Sw 

Decies  spinosus  Say 

Coptocycia  bicolor  Fab 

Coplocycla  signifera  Herbst    

Epicauta  marginata  Fab 

Epicauta  pcnnsylvanica  DeG 

Lixus  macer  Lee 

Chclymorpha  argus  Herbst 

Languria  angustata  var.  trifasciata  Say. 

Acrapteryx  gracilis  Newm 

Odontota  nervosa  Panz 

Pelidnola  punctata  Linn 

Doryphora  clivicollis  Kirby 

Lebia  atriventris  Say 

Elaphidion  villosum  Fab , 

Callida  punctata  Lee 

Megamclus  marginatus  Van  D 

Crabro  interruptulus  D.T.  ._ 

Chloral  ictus  cressoni  Rob 

Helobia  hybrida  Meig 

Pachyrhina  ferruginca  Fab 

Coenomyia  ferruginca  Scop 

Straiissia  longipennis  Wied 


Month 


69 

69 

6 

69 

6 

6 

8 

6 

6 

6 

6 

6 

6 
6  7 

7 

7 

7 


6  8 
6 
6 


3 
5 
4  5 
5 
5 
5 


CHAPTER  XIV 

PRAIRIE  ANIMAL  COMMUNITIES 

I.    Introduction 

We  have  noted  that  a  part  of  the  region  about  Chicago  is  to  be 
classed  as  savanna  and  that  the  savanna  is  made  up  of  trees  in  groves 
and  along  the  streams,  and  of  forest  margin  and  prairie.  Prairie  may 
roughly  be  separated  into  high  and  low.  The  low  prairie  commonly 
exists  in  depressions  in  the  moraine,  lower  places  in  the  plain  of  old 
Lake  Chicago.  They  are  usually  covered  with  water  in  the  spring. 
The  high  prairie  is  above  water  and  is  dominated  by  different  plants. 
As  the  depressions  are  filled  or  become  better  drained,  high  prairie 
plants  capture  the  habitat. 

II.     Prairie  Formations 

We  have  noted  that  the  low  prairie  is  covered  by  water  in  spring 
(Figs.  280,  281).  As  the  water  dries  up,  which  usually  occurs  by  the 
middle  of  May,  the  prairie  plants  begin  to  grow  and  the  prairie  animals 
make  their  appearance.  This  change  does  not  take  place  abruptly, 
but  gradually.  There  is  a  succession  of  adult-stage  animals  through 
the  summer.     This  is  what  is  known  as  seasonal  succession. 

I.      SEASONAL   SUCCESSION 

When  the  snow  melts  in  March  and  the  frost  goes  out  of  the  ground, 
the  salamander  (Amblystoma  tigrinum)  comes  out  of  the  ground  and 
soon  deposits  masses  of  eggs  in  the  water.  The  young  of  Eubranchipus, 
Cyclops,  and  rotifers  appear  after  a  few  days  and  often  reach  adult  size 
by  April  i.  On  April  6,  1908,  Mr.  Dimmit  found  adult  Eubranchipus, 
Cyclops,  and  rotifers  in  the  pond  south  of  Jackson  Park.  The  sala- 
manders had  disappeared.  On  April  12  three  species  of  flatworms 
{Vortex  viridis,  Planaria  velata  Stringer,  and  Dendrococlum)  had  appeared, 
and  the  first  frogs  were  noted.  On  April  14  he  found  frogs'  eggs  and 
the  red  crustacean  (Diaptomus).  Eubranchipus  was  at  its  maximum 
abundance.  On  April  19  he  found  Daphnidae,  rhabdocoel  worms,  and 
tadpoles.  On  May  3  but  few  Eubranchipus  were  found.  Diaptomus  was 
plentiful,  perhaps  at  its  maximum  abundance.  Daphnidae  was  more 
abundant  than  before.    Planaria  were  near  their  maximum.    On  May  10 

278 


LOW  PRAIRIE 


279 


Eiibrauchipus  serratiis  had  disappeared  and  Diaptomus  was  not  common. 
Our  next  record  is  one  month  later,  when  the  grasshoppers  and  other 
prairie  or  land  species  had  begun  to  appear.  This  succession  is  of 
annual  occurrence.  The  temporary  pond  community  is  seasonally 
succeeded  by  the  low  prairie  community.     Flies  which  breed  in  water, 


Fig.  280. — \  prairie  pond,  still  permanent. 

Fig.  281. — A  temporary  prairie  pond  in  spring.     The  short  dead  grass  indicates 
that  a  crop  was  harvested  the  preceding  season. 

such  as  Scoliocentra  (Fig.  282)  and  Tetanocera  (Fig.  283),  are  common 
(also  Figs. "284,  285,  286). 


2.      LOW   PRAIRIE   ASSOCIATION 

o)  The  subterranean-ground  stratum  (Stations  42,  43,  44,  45;  Table 
LXV). — Earthworms  are  abundant.  Several  of  the  grasshoppers  de- 
posit their  eggs  in  the  ground.     The  larvae  of  the  click-beetle  {Melanotus 


28o 


PRAIRIE  COMMUNITIES 


282 


283 

Fig.  282. — A  low  prairie  fly  {ScoUocenlra  helvola  Loew);  enlarged. 
Fig.  283. — A  low  prairie  fly  (Tetanocera  umbranim);  enlarged. 


Z.  P 

LOW  PRAIRIE 


"    '-rr  I  r    OP 


2«I 


284 


Some  Low  Prairie  Flies 
Fig.  284. — Pipunculus  fusciis  (after  Lugger  from  Williston).   , 
Fig.  285. — Tahanits  lincola  Fabr.  (after  Lugger  from  Williston). 


Fig.  286. — Spilogaster  sp.  from  Williston,  who  says  it  inhabits  high  grass. 


2«2 


PRAIRIE  COMMUNITIES 


fissilis),  of  the  strawberry  flea-beetle  (Typophorus  canellus),  and  the 
corn  rootworms  (Diabrolica)  (174),  and  of  many  other  insects  well 
known  in  economic  literature,  burrow  into  the  roots  of  the  plants  in  the 
larval  stage.  Many  of  the  grass-eating  cutworms,  caterpillars,  and 
sawflies  (Fig.  287)  pupate  beneath  the  surface  of  the  ground.  The 
salamander  (Amblystoma  tigrinum)  spends  ten  months  of  each  year  buried 
in  the  mud  of  such  temporary  ponds.  The  Pennsylvania  meadow-mouse 
(Microtus  pennsylvanicus  Or.)  has  been  common  in  these  situations. 


Fig.  287. — Grass  sawflies:  a,  eggs;  b,  larvae  (a  and  b  natural  size);  c,  larva; 
d,  cocoon;  e,  adult  male;  /,  adult  female  (c  to /enlarged  as  indicated)  (after  Marlatt, 
Insect  Life). 


The  star-nosed  mole  burrows  beneath  the  sod.  It  is  remarkable  for  its 
curiously  fringed  nostril.  The  wetness  of  the  ground  excludes  other 
burrowing  mammals. 

One  of  the  most  abundant  forms  found  here  is  the  snail  {Succinea 
avara).  The  ant  {Formica  subpolita  var.  neogagates  Em.)  is  also  usually 
common.  It  builds  a  hill  and  burrows  below  the  surface  of  the  ground 
also.  Several  snout-beetles,  the  adult  click-beetles,  and  the  short- 
winged  grouse  locust  {Tettigidea  parvipennis  and  pennata)  are  common 


LOW  PRAIRIE 


283 


on  the  ground.  The  6-spotted  spider  {Dolomedes  sexpunctatus)  preys 
upon  the  other  small  animals.  The  common  toad  and  the  marsh  tree- 
frog  {Chorophilus  nigritus)  are  common  (139).  The  latter  is  particularly 
abundant  in  the  autumn.  Its  eggs  are  laid  in  April  in  the  temporary 
pools.  Transformations  are  complete  by  the  last  of  May.  The  prairie 
garter-snake  {Thamnophis  radix)  was  formerly  common.  It  is  known  to 
feed  upon  the  swamp  tree-toad.  The  prairie  water-snake  (Tropidonotus 
grahamii)  was  formerly  common  in  and  about  prairie  sloughs  (22). 

The  bobolink  builds  a  nest  here  in  a  bunch  of  grass;  the  meadow 
lark  and  dickcissel  build  nests  of  grass  and  weeds,  usually  arched  over. 
The  bisons,  residents  of  the  high  prairie,  were  fond  of  roUing  in  the  low 


288 

Fig.  288. — The   large    green    leaf-hopper 
^  (Draeculacepftala  mollipes):    o,  young;   6,  one 
half-grown;   c,  adult;    enlarged  as  indicated 
(after  Forbes). 

Fig.  289. — The  six-spotted  leaf  hopper 
{Cicadula  sexnotala);  enlarged  as  indicated 
(after  Forbes). 


lA^ 


289 


wet  places  on  the  prairie  and  covering  themselves  completely  with  mud. 
This  must  have  destroyed  numbers  of  pond  animals  and  badly  disturbed 
others. 

b)  The  field  stratum  (Stations  42,  43,  44,  45;  Table  LXVI).— This 
is  the  chief  stratum.  While  various  conditions  of  the  subterranean 
and  ground  strata,  depending  upon  nearness  to  ground  water,  could  be 
recognized,  our  studies  have  not  been  sufficiently  detailed  to  warrant 
attempts  at  separation.  A  girdle  of  bulrushes  can,  however,  often  be 
distinguished. 

Bulrush  girdle:  Two  of  the  large  green  leaf-hoppers  (Draeculo- 
cephala  mollipes  [Fig.  288]  and  Cicadula  6-notata  [Fig.  289])  are  common. 
The  damsel-bug  (Reduviolus  ferus),  which  feeds  upon  leaf-hoppers,  is 


284  PRAIRIE  COMMUNITIES 

sometimes  taken.  The  slender  meadow  grasshopper  (Xiphidium  fasci- 
tauni)  is  common,  but  breeds  in  the  sedge  zone.  A  flea-beetle  {Monachus 
saponatus),  the  12-spotted  Diabrotica  {Diabrotica  12-punctata)  (156), 
and  the  salt-meadow  snout-beetle  {Endalus  limatulus)  (156)  are  the 
chief  beetles. 

The  spiders  (Epeira  trivitlata  and  Tetragnalha  labonosa)  are  common. 

The  flies  of  this  girdle  are  perhaps  the  most  noteworthy  insects      Several 

species  of  brownish  or  yellowish  flies  with  conspicuously  marked  wings 

are  nearly  always  common.     They  are  Sciomyzidae  {Tetanocera  plumosa 

a.nd  umbr arum)  (Fig.  283).     Other  characteristic 

flies   are   Osinidae   {Chlorops  sulphurea  Leow.), 

midges,  mosquitoes,  Dolic/iopodidae,  Rosophilidae, 

and  Anlhomyidae.     The  blue  and  yellow  moth 

(Scepsis  fulvicollis)  is  common. 

Boneset  and  sedge  girdle:  The  buffalo  tree- 
hopper  (Cere^a  bubalus)  (Fig.  259)  is  found  here. 
The  dusky  (Fig.  261)  and  tarnished  plant-bugs 
(Fig.  262)  suck  the  juices  of  the  mint  and  other 
plants.  The  ambush-bug  and  the  damsel-bug 
often    lie   in    wait    in    the    blossoms    for   prey. 


290 

Fig.  290. — Larva  of  the  salt-marsh  caterpillar  {Estigmcim  acraca  Dru.);  natural 
size  (after  Forbes) . 

Fig.  291. — Adult  female  of  the  same;   natural  size  (after  Forbes). 

Aphids  occur  and  with  them  are  the  syrphus  flies,  lady-beetles, 
and  other  aphid  enemies  (164),  which  are  discussed  more  fully  in 
connection  with  high  prairies.  The  bright  green  beetle  iChryschus 
auratus)  feeds  on  the  small-leafed  milkweed.  One  of  the  corn  "bill- 
bugs"  (174)  or  snout-beetles  (Sphenophorus  pertinax  Oliv.),  another 
snout-beetle  (Cryptocephalus  venustus),  common  garden  pests,  as  well  as 
the  leaf-beetle  {Typophorus  canellus)  are  common  (174). 

One  of  the  most  characteristic  groups  of  the  low  prairie  is  that  of  the 
grass-feeding  larvae.     The  first  of  these  to  appear  in  spring  is  the  grass 


LOW  PRAIRIE 


285 


sawfly  (Fig.  287),  which  is  very  abundant  in  early  June.  Associated 
with  this  are  many  caterpillars  (174)-  The  greasy  cutworm  (Agrotis 
ypsilon  Rett.)  feeds  upon  the  strawberry.  The  army  worm  {Lucania 
unipuncta  Haw.)  feeds  upon  a  \-ariety  of  j^lants,  and  several  of  its  near 
relatives  occur.  The  larvae  of  the  salt-marsh  caterpillar  {Esligmene 
acraea)  (Figs.  290,  291),  the  yellow  bear  (Diacrisia  virginica  Fab.)  (Fig. 
292),  hedgehog  caterpillar  {Isia  Isabella  S.  and  A.),  and  Apantesis 
phalterta  Harr.  are  common. 

Of  the  Orthoptera,  Xiphidium  fasciatum  and  the  2-lined  locust  {Melano- 
pliis  bivittatus),  the  red-legged  locust  {Melanoplus  femur-rubrum),  and 
the  short-winged  brown  locust  {Stenobothrus  ciirtipennis)  (Fig.  293) 
are  most  characteristic. 


293 

Fig.  .292. — The  jellow  bear:  a,  larva; 
/»,  adult  (Diacrisia  virginica  Fabr.);  nat- 
ural size  (after  Forbes). 

Fig.  293. — The  short-winged  brown 
locust  {Stciiobotliriis  ciirtipennis)  (after 
Lugger). 


On  the  flowers  are  many  flower-frequenting  flies,  viz.,  SparnopoUus 
flavius  Wied.,  Asilus  sp.,  Syritla  pipiens  Linn.,  Coenosia  spinosa  Walk., 
Paragus  angiistlfrons  Loew.,  Pachryrhina  ferruginea,  and  Helophilus 
conostoma  Will.  Preying  upon  the  various  insects  are  the  mud-dauber 
wasp  (Scelipron  cementarius)  and  the  digger-wasp  (Ammophila  nigricans). 
Parasites,  such  as  Ichneumon  zebratus,  Paniscus  gemminatus,  Epeolus 
cressonii,  etc.,  occur  upon  the  plants,  and  certain  of  them  are  often 
found  engaged  in  depositing  eggs  in  or  on  caterpillars.  The  onion-fly 
{Tritoxa  flexa)  (190)  is  striking  because  of  its  black  body  and  black 
wings,  obliquely  marked  with  white. 

Spiders,  especially  crab  spiders,  are  abundant.  The  white  Misimena 
vatia  occurs  on  the  milkweed  and  the  flowers  of  the  mint.  Epeira 
trivittata  and  the  long-bodied  spider  {Tetragnatha  laboriosa)  occur  on  the 
blossoms  and  stems  of  various  plants. 


286  PRAIRIE  COMMUNITIES 

HIGH   PRAIRIE   ASSOCIATION 

(Stations  47,  48;  Table  LXVII)  (Fig.  294) 

The  type  of  vegetation  which  dominates  the  high  prairie  is  most 
noticeably  characterized  by  the  silphiums — the  rosin-weed  and  the  com- 
pass plant.  The  former  has  broad  undivided  leaves,  the  latter  divided 
leaves  which  usually  face  east  and  west.  This  plant  formation  springs 
up  throughout  the  temperate  American  forest  border  area  on  all  well- 
drained  ground.  It  succeeds  the  low  prairie  as  the  depressions  occupied 
by  the  latter  are  filled  or  drained.  The  high  prairie  then  succeeds  the 
low  prairie  just  as  the  bulrushes  succeed  the  pond  plants;  the  sedges, 
the  bulrushes;  and  the  boneset  association,  the  sedges.  All  stages  in 
the  development  of  a  pond  into  prairie  may  be  found  near  Chicago. 
Dr.  Cowles  is  of  the  opinion  that  shallow  ponds  with  gently  sloping 
sides  develop  into  prairie,  while  deeper  ponds  with  steep  sides  develop 
into  forest. 

a)  Subterranean- ground  stratum. — Earthworms  abound.  The  larvae 
of  the  May-beetles  and  other  Scarabaeidae  are  abundant,  feeding  on  the 
roots  of  the  prairie  plants.  The  May-beetle  is  often  parasitized  by  a 
wasp  larva  (Tiphia  vulgaris)  (Fig.  297,  p.  289)  (189).  The  eggs  of  the 
2 -lined  locust  {Melanoplus  bivittatus)  are  deposited  here  in  the  ground. 

The  13-lined  ground  squirrel  {Citellus  ij-lineatus)  (21)  is  a  slightly 
gregarious  species,  strictly  diurnal,  staying  in  during  dull  and  cloudy 
days.  Its  burrows  are  from  3  to  16  in.  below  the  surface,  and  often  have 
five  or  six  entrances  into  a  larger  cavity  lined  with  grass.  In  a  den 
studied  by  Thompson-Seton  the  nest  was  centrally  located.  Food, 
which  includes  cabbage  butterflies,  cutworms,  grasshoppers,  beetles, 
ants,  birds  (shore  lark  and  lark  bunting),  and  vegetation,  is  carried  in 
the  cheek  pouches  and  stored.  The  species  is  non-social.  A  brood  of 
about  eight  young  are  produced  in  April. 

The  prairie  deer-mouse  (Peromyscus  bairdii  H.  and  K.)  (21)  is  still 
probably  common.  According  to  Thompson-Seton  (143)  its  home  range 
is  about  TOO  yds.  It  is  neither  social  nor  gregarious.  It  is  strictly 
nocturnal  and  active  all  winter,  though  some  seeds  are  stored.  Its 
food  is  chiefly  seeds.     Hawks  and  owls  frequently  prey  upon  it. 

Of  the  extinct  forms  several  are  characteristic.  The  coyote  (Canis 
latrans  Say)  was  formerly  common.  According  to  Thompson-Seton 
(143),  its  home  range  is  ten  miles.  The  den  is  in  a  bank  or  an  abandoned 
badger  hole.  The  nest  is  a  cavity  3  ft.  in  diameter,  with  an  air-shaft. 
It  is  not  so  social  as  the  gray  wolf.     Three  to  ten  young  are  produced 


HIGH  PRAIRIE 


287 


O 


288 


PRAIRIE  COMMUNITIES 


in  April  and  are  fed  on  disgorged  food  by  the  mother.  The  food  con- 
sists of  ground  squirrels,  mice,  rabbits,  frogs,  birds,  and  grasshoppers. 

The  badger  (Taxidea  taxus  Schr.),  according  to  Thompson-Seton, 
digs  a  U-shaped  burrow  with  two  openings  about  6  ft.  deep.  It  is  a 
very  rapid  burrower.  It  is  nocturnal,  but  basks  in  the  sun  at  the 
mouth  of  its  burrow  and  hibernates.  Its  food  consists  of  mice  and 
ground  squirrels. 

The  pocket  gopher  (Geomys  hur sarins  Shaw) ,  according  to  Thompson- 
Seton,  makes  a  burrow  3  in.  wide.     It  burrows  with  its  feet  and  when 


Fig.  295. — The  nest  and  eggs  of  the  prairie  chicken.     Photo  by  T.  C.  Stephens. 


a  pile  of  dirt  has  been  loosened,  turns  about  and  forces  it  to  the  exterior 
with  its  head.  The  coyote  sometimes  rears  its  young  in  badger  holes  on 
the  prairies. 

On  the  ground  we  find  ants  {Myrmica  rubra  scabrinodis),  one  thou- 
sand of  which  were  found  by  Judd  (191)  in  the  stomach  of  a  single  night- 
hawk.  Ground  beetles  are  common.  Crickets,  spiders,  and  weevils 
all  frequent  the  ground.  Most  of  the  field  stratum  species  hibernate 
on  the  ground  under  the  fallen  plants. 

The  common  toad  is  rarely  wanting  near  water.  The  garter-snake 
{Thamnophis  radix)  has  been  recorded  by  Ruthven  (156)  from  such 


HIGH  PRAIRIE 


289 


situations  in  Iowa.  The  green  snake  {Leopeltis  vernalis)  is  the  most 
characteristic  reptile.  The  prairie  rattlesnake  or  Massasauga  {Sis- 
Irurns  calenatus)  was  formerly  common  (22). 

Eight  nesting  birds,  all  of  which  are  quite  familiar  to  everyone,  occur. 
The  bobolink  nests  in  a  bunch  of  grass.  It  feeds  upon  flea-beetles, 
weevils,  ants,  bees,  wasps,  and  grasshoppers  of  the  field  stratum.  The 
meadow  lark  feeds  on  parasitic  hymenoptera,  including  the  parasite  of  the 
May-beetle,  ground  beetles,  crickets,  grasshoppers,  weevils,  spiders,  etc. 
The  dickcissel  is  similar  in  habits.  The  grasshopper  sparrow  feeds  on 
long-horned  grasshoppers,  flea-beetles,  cutworms,  and  parasitic  hymen- 
optera. The  vesper  sparrow  feeds  upon  moths,  flies,  ants,  beetles, 
grasshopper  eggs,  etc.,  and  grain  and  weed  seeds.  The  nighthawk 
builds  no  nest,  flies  at  twilight,  and  feeds  chiefly  upon  ants.     The 


297 

Fig.  296 — The  adult  of  the  wasp  which 
is  parasitic  on  the  May-beetle  grubs 
(Tiphia  vulgaris)  (after  Forbes). 

Fig.  297. — The  larva  of  the  same  (after 
Forbes). 


prairie  chicken  is  the  most  characteristic  bird.  Its  nest  is  a  simple 
hollow  in  the  grass  (Fig.  295).  The  prairie  horned  lark  builds  a  nest 
lined  with  thistledown  and  feathers.  The  lark  bunting  nests  in  a  tuft 
of  grass. 

All  of  the  mammals  noted  in  the  subterranean  stratum  should  be 
added  here,  as  nearly  all  of  them  feed  largely  in  the  ground  and  field 
strata. 

The  field-mouse  (Microtus  ochrogaster  Wagner)  (21)  is  a  resident  of 
the  ground  stratum.  Its  nest  is  a  pile  of  grass  fragments  on  the  ground. 
The  species  feeds  chiefly  upon  grasses  and  cultivated  plants.  The 
bison  {Bison  bison  Linn.)  is  the  most  characteristic  mammal.  Thompson- 
Seton  says  that  the  bison  population  of  North  America  was  originally 
75,000,000.  This  animal  generally  went  in  clans  or  families  which  are 
said  to  have  had  characteristics  of  their  own.     An  old  cow  was  the 


290 


PRAIRIE  COMMUNITIES 


usual  leader  of  the  clan.  On  the  great  plains  these  united 
and  formed  the  larger  herds  of  20,000  to  4,000,000  or  more, 
which  have  been  described  by  travelers.  The  males  aided 
in  defending  the  young.  The  cowbird  is  said  to  have  fol- 
lowed the  herds  constantly. 

b)  Field  stratum. — The  lepidopterous  larvae  are  similar 
to  those  of  the  low  prairie,  but  much  less  numer- 
ous.    The  hymenoptera  are  represented  by  Bom- 
bus  separatus,  and  many  of  those  recorded  on  the 
low  prairie.     The  adult  of  the  parasite  (Tiphia 
vulgaris)  of  the  May-beetle  larva 
(Figs.  296-97)  occurs  commonly. 
Several    species    of    aphids   (Figs. 
298-300)  occur,  especially  on  the 


milkweeds    and    thistles. 
These  are  commonly  at- 
/  tended    by    ants,    which 

stroke  them  and  secure  the  honey  dew  from 
the  posterior  ends  of  their  alimentary  canals. 
The  aphids  reproduce  rapidly,  the  young  being 
born  in  rapid  succession  at  a  very  ad- 
vanced   state    of    development.      They 
begin  sucking  the  juices  of   the  plant 
at  once.     Several  small  parasitic 
hymenoptera  (braconids)    (Fig. 
299)  lay  their  eggs  in  the  bodies 
of  the  aphids.     These  finally  kill 
the  aphids,  whose  bodies  with 

Fig.  298. — A  viviparous  grain  louse  {Macrosiphmn  granaria  Kirby)  with  her 
newly  born  young  on  a  barley  leaf  (after  Washburn,  Bull.  108,  Minn.  Agr.  Exp.  Sta., 
Fig.  2,  p.  262). 


HIGH  PRAIRIE 


291 


300 

Fig.  299. — A  parasitic  wasp  depositing 
eggs  in  the  body  of  a  grain  louse  (after 
Washburn,  Bull.  108,  Fig.  16,  p.  274). 

Fig.  300. — A  louse  killed  by  a  parasite 
(after  Washburn,  loc.  cit.,  Fig.  12,  p.  276). 


Fig.  301. — The  life  history  of  the  golden-eyed  lacevving  {Clirysopa  oculata)'. 
a,  eggs;  h,  the  larva — "aphis-lion";  c,  foot  of  the  larva;  d,  the  larva  seizing  an  aphid; 
e,  the  pupal  cocoon;  /,  g,  h,  the  adult;  h,  natural  size  (after  Chittenden,  Div.  Ent., 
U.S.  Dept.  Agr.). 


292 


PRAIRIE  COMMUNITIES 


small  circular  openings  on  the  abdomen  can  often  be  seen  sticking  to 
the  food  plant  (Fig.  300).  The  aphis-lion,  which  is  the  larva  of  the 
golden-eyed  lacewing,  feeds  upon  them  (Fig.  301).  The  eggs  of  the 
lacewing  are  pecuUar  in  that  each  is  attached  to  a  stalk.  This  is 
supposed  to  be  an  adaptation  preventing  the  larvae  already  hatched 
from  devouring  the  remaining  eggs.  The  larva  of  the  syrphus  fly 
(Mesogramma  sp.)  (Fig.  302)  devours  the  aphids  in  numbers.  Lady- 
beetles,  both  adults  and  larvae  (Hippodamia  parenthesis  Say,  Megilla 
maciilata)  (Fig.  303),  eat  aphids. 

In  June  the  narrow  leaf-bug  {Miris  dolohrata)  and  the  dark  leaf-bug 
(Horcias  goniphorus)  are  usually  very  abundant;  both  are  characteristic. 


Fig.  302. — A  syrphus  fly  {Mesogramma  polita),  adult  (after  Forbes):  a,  the 
larva  which  feeds  on  aphids;  b,  pupa;  enlarged  as  indicated  (from  Forbes  after 
Riley  and  Howard,  Div.  Ent.,  U.S.  Dept.  Agr.). 


Later  in  the  season  their  places  are  taken  by  several  others  {Lygus 
pratensis  and  Adelphocoris  rapidus).  The  garden  flea-hopper  {Halticus 
uhleri)  occurs  on  the  under  side  of  leaves.  The  squash -bug  family  is 
represented  by  Alydus  cons  per  sus. 

The  tree-hoppers  are  represented  by  the  buffalo  tree-hopper  {Ceresa 
huhalus),  and  the  curve-horned  trtt-\iop^tr  ^{Campylenchia  curvata). 
The  only  lantern-fly  recorded  is  Amphiscepa  hivittata.  Leaf -hoppers  are 
numerous;  about  ten  species  have  been  taken. 

The  species  of  Orthoptera  are  mainly  different  from  those  of  the  low 
prairie.  The  2-lined  and  short-winged  brown  locusts  still  continue. 
Xiphidium  sirictum  (Fig.  304)  takes  the  place  of  fasciatum.  The  com- 
mon meadow  grasshopper  {Orchelimum  vulgare)  and  an  occasional  Texas 


HIGH  PRAIRIE 


293 


katydid  {Scudderia  texensis)  are  taken  from  the  goldenrod.  From  the 
goldenrod  we  also  take  the  goldenrod  beetle  (Trirhabda  tormentosa 
wdiX .  canadensis)  and  the  case-bearer  (Pachybrachys) .  The  lady-beetles 
(Cycloneda,  Hippodamia,  Megilla,  etc.)  are  common.  The  clover-leaf 
beetle  {Languria  mozardi?)  (Fig.  305)  is  also  of  common  occurrence. 
The  snout-beetles  are  represented  by  the  large,  elongated  Lixus  (Fig. 
306),  the  larvae  of  which  feed  in  the  stalks  of  rank  weeds. 


Fig.  303. — ^The  lady-beetle  {Megilla  maciilata  DeG.)  and  its  life  history:  a, larva; 
6,  pupa;  c,  adult  (Chittenden,  U.S.  Dept.  Agr.);   enlarged  as  indicated. 


Fig.  304. — Meadow  grasshopper  {Xiphidiiim  strictum  Scud.);   twice  natural  size 
(after  Forbes) . 


The  onion-fly  occurs  in  connection  with  the  prairie  onion.  Eristalis 
tenax  is  common  on  the  flowers.  Various  flower-flies  occur.  Waiting 
in  the  flowers  for  such  animals  as  may  come  are  the  ambush-bugs  {Phy- 
mata  e'rosa  fasciata),  and  the  crab  spiders  (Misumessus  asperatus  and 
Runcina  aleatoria).  The  jumping  spiders  {Phidippus  podagrosus)  are 
also  predatory  (138).  The  orb-weavers  (Epeira  trivittata,  Agriope 
trifasciata)  build  webs  into  which  many  insects  fall. 


294 


PRAIRIE  COMMUNITIES 


HH 

i^Bm 

^^^H 

^^^^^^ 

^|IfI^*^^^nS 

1%!!^^HH 

Kk.«'A 

flB 

Fig.  305. — The  clover-stem  borer  {Langttria  mozardi  Lee):  a,  the  egg;  b,  c,  the 
larva;  d,  the  pupa;  e,  the  adult;  much  enlarged  (after  Folsom  from  Forbes). 


PRAIRIE  ANIMALS 


295 


III.  General  Discussion 
One  of  the  striking  peculiarities  of  the  prairie  formation  is  the  almost 
complete  cessation  of  life  activities  of  all  the  smaller  animals  in  winter. 
In  this  respect  the  prairie  animals  follow  the  plants.  In  spring  we  find 
chiefly  the  insignificant  seedling  that  has  sprouted  from  bulb  or  seed, 
and  the  nymph  that  has  just  hatched  from  the  egg.  As  the  season 
advances  the  plants  become  adult,  the  majority  of  these  reaching 
maturity  with  the  animals  in  midsummer. 


Fig.  306.— The  dock  curculio  {Lixus  concavus  Say) :  a,  adult;  b,  egg;  c,  d  newly 
hatched  and  full-grown  larva;  e,  pupa;  /,  tip  of  pupa  from  above;  about  twice  natural 
size  (from  Forbes  after  Chittenden,  Div.  Ent.,  U.S.  Dept.  Agr.). 


The  low  prairie  is  of  interest  because  of  its  relation  to  the  eastern 
forest  region.  Many  if  not  most  of  the  low  prairie  forms  probably 
origmally  occurred  in  the  marshes  of  the  eastern  forest  region  and  the 
river-bottom  swales  of  the  prairie  and  great  plains.  Many  of  them 
(such  as  place  their  eggs  into  plants)  are  quite  independent  of  the  ground, 
and  therefore  are  most  likely  to  survive  under  conditions  of  cultivation 
where  mesophytic  plants  are  favored  and  the  cultivation  of  the  soil 
does  not  interfere  with  their  activities. 


296 


PRAIRIE  COMMUNITIES 


TABLE  LXV 

Low  Prairie  Animals  Inhabiting  the  Ground 
R  =  Riverside  (Station  48);  W=near  Wolf  Lake  (near  Station  45);  J  =  south  of 
Jackson  Park  (Stations  42,  43). 


.  Common  Name 

Scientific  Name 

HabiUt 

Craj^sh 

Cambarus  diogenes  Gir 

R 
R 
R 
R 
R 
R 

R 

R 
R 

J 
J 
J 
J 
J 
J 

Cra\'fish   

Cambarus  gracilis  Bun 

Ground  beetle 

Chlaenius  aestivus  Say 

Platynus  affinis  Kirby 

Amara  angustata  Say 

Ground  beetle 

Ground  beetle 

Spider 

Ozyptila  conspurcata  Thor 

Diplochila  laticollis  Lee 

Salda  coriacea  Uhl 

Amblystoma  tigrinum  Green 

Rana  pipiens  Sch 

Acris  gryllus  Lee 

Chorophilus  nigritus  Lee 

Biifo  lentiginosus  Shaw 

Thamnophis  radix  B.  and  G.?. . . 

Beetle   

Shorebug 

Salamander 

Frog 

W 

Cricket-frog 

W 

Swamp  tree-frog 

w 

Toad 

w 

Garter-snake 

TABLE  LXVI 
Low  Prairie  and  Temporary  Marsh  Animals  Frequenting  the  Vegetation 
B  =  the  triangular  bulrush  belt  about  Wolf  Lake  (Station  45);    S  =  the  sedge 
belt  of  the  same;  J  =  sedge  prairie  south  of  Jackson  Park  (Stations  42,  43);  R  =  sedge 
prairie  near  Riverside  (Station  48),  June  15  to  August  30. 


Common  Name 


Spider 

Diving  spider 

Spider 

Long-bodied  spider. .  .  . 

Crab  spider 

White  crab  spider 

Striped  spider 

Garden  spider 

Small  orb- weaver 

Tube- weaver 

Slender  meadow  grass- 
hopper   

Short-winged  brown  lo- 
cust   

Meadow  grasshopper.  . 

Red-legged  grasshopper 


Scientific  Name 


Eugnatha  straminea  Em 

Dolomedes  sexpunctatus  Htz. .  . 

Epeira  trivitlata  Key 

Tetragnatha  laboriosa  Htz 

Runcinia  aleatoria  Htz 

Misumena  vatia  Clerck 

Argiope  trijasciata  Forsk 

Argiope  aurantia  Luc 

Epeira  trifolium  Htz 

Agelena  naevia  Walck 

Xiphtdium  fasciatum  DeG .... 

Stenobothrtis  curtipennis  Harr. . 

Orchelimum  vulgare  Harr 

Melanoplus  fetnur-rubrum  DeG 


Habitat 


B 

B 

B 

S 

T 

B 

S 

T 

s 

J 

J 
J 

B  • 

s 

J 
J 

B 

s 

J 

R 

s 

T 

R 

s 

J 

s 

J 

R 

PRAIRIE  ANIMALS 
TABLE  LXVI— Continued 


297 


Common  Name 


Texas  grasshopper .  .  . 

Cockroach 

Cricket 

2-lined  locust 

Green-legged  locust .  . 

Capsid  bug 

o  6-spotted  leaf-hopper. 
(5  Large  leaf- hopper .... 

Damsel-bug 

D  Leaf- hopper 

O  Leaf-hopper 

^  Leaf-hopper 

O  Leaf-hopper 

Tarnished  plant-bug. .  . 
O  Brownie  bug 

Dusky  plant-bug 

Leaf-hopper 

Ambush-bug 

Long-horned  leaf-beetle 

Cornroot  worm-beetle. 

Marsh  snout-beetle. .  .  . 

Buprestid 

Leaf-beetle 

Click-beetle 

Green  beetle 

Chrysomelid 

Chrysomelid 

Case-bearer 

Milkweed  beetle 

Goldenrod  beetle 

Snout-beetle 

Fly 

Cloudy-winged  fly.  .  .  . 

Long-legged  fly 

Syrphus  fly 

Onion- fly 

Ant 

Syrphus  fly 

Bee 

Bumblebee 

Lacewing 

Ant 

Ichneumon  fly 

Moth 

Syrphus  fly 

Social  wasp 


Scientific  Name 


Scudderia  texensis  S.  and  P. . , 

Blattid  sp 

Nemobius  maculatus  Blatch.  . 
Melanoplus  biviUalus  Say. ... 
Melanoplus  viridipes  Scud.  .  .  , 

Teratocoris  discolor  Uhl , 

Cicadula  sexnotata  Fall , 

Dracculaccphala  moUipes  Say . . 

Reduviolus  ferus  Linn 

Chlorotettix  unicolor  Fitch. ... 
Helpchara  communis  Fitch ... 

^Attiysanus  striolus  Fall 

Chlorotettix  tergata  Fitch 

Lygus  pratensis  Linn 

Campylenchia  ciirvata  Fab .  .  . 
Adetphocoris  rapidus  Say. .  .  . 
Athysanus  parallelus  Van  D .  . 
Phymala  erosa  fasciata  Gray . 

Donacia  subtilis  Kunze 

Diabrotica  12-punctata  Oliv .  . 

Endalus  limatuhis  Gyll 

Acmaeodera  pulchella  Hbst. .  . 

Monachus  saponatiis  Fab 

Melanotus  fissilis  Say 

Chrysochus  auratus  Fab 

Nodonola  tristis  Oliv 

Typophorus  canelliis  aterrimus 

Oliv 

Cryptocephalus  venustus  Fab. 
Cryptocephalus  cinctipennis 

Rand 

Tetraopes  tetraophthalmus  Forst 
Trirhabda  canadensis  Kirby.  . 

Desmoris  scapalis  Lee 

Tetanocera  iimbrarum  Linn .  .  . 
Tetanocera  plumosa  Loew.  .  .  . 

Dolichopodidae  sp 

Syrphus  americanus  Wied.  . . . 

Tritoxa  flexa  Wied 

Formica  subpolita  neogagates 

Emery 

Eristalis  tenax  Linn 

Agapostemon  viridulus  Fab .  .  . 

Bombiis  separatus  Cress 

Chrysopa  albicornis  Fitch 

Myrmica  rubra  scabrinodis  Nyl. 

Ichneumon  galenus  Cress 

Scepsis  fulvicollis  Hbn 

Mesogramma  geminata  Say. .  .  . 
Polistes  variatus  Cress 


Habitat 

s 

s 

T 

s 

J 

s 

J 

s 

,T 

B 

s 

r 

B 

s 

T 

B 

s 

T 

B 

s 

J 
J 

.T 

B 

s 

1 

s 

J 

s 

1 

B 

s 

J 

.T 

s 

I 

B 

B 

s 

T 

B 

B 

s 

B 

s 

T 

s 

T 

s 

J 
J 

s 

J 
J 

! 

B 

J 

B 

I 

s 

J 

s 

J 

.T 

s 

J 
J 
J 
J 
J 
J 

B 

s 

T 

s 

J 

298 


PRAIRIE  COMMUNITIES 


TABLE  LXVII 

Animals  Usually  Common  on  Compass-Plant  Prairie 
Collections  made  near  Riverside  (Station  48)  and  Chicago  Lavra  (Station  47), 
June  IS  to  August  30. 


Common  Name 


Scientific  Name 


Cricket. 

Jumping  spider 

Jumping  spider 

Jumping  spider 

Jumping  spider 

Harvestman 

Garden  spider 

Ant 

Grasshopper 

Meadow  grasshopper 

Meadow  grasshopper 

Brown  locust 

Conehead 

Katydid 

C  Leaf -hopper 

CLeaf-hopper 

^^  Leaf-hopper 

Leaf-bug 

Leaf-bug 

O  Leaf-hopper 

^  Membracid 

Garden  flea-hopper .  . 

Stinkbug 

Leaf-bug 

Leaf-hopper 

^'  Leaf-hopper 

Negro-bug 

Coreid 

Stinkbug 

Leaf-bug 

Leaf-bug 

Beetle  (Mordellid)  .  . 

Lady-beetle 

Case-bearer 

Strawberry  beetle.  .  . 

Beetle 

Syrphus  fly 

Green  snake 


Nemobius  fascialus  vitlatus  Harr. 
Maevia  niger  Htz. 
Phidippus  podagrosus  Htz. 
Phidippus  borealis  B. 
Phidippus  rufus  Htz. 
Liobtinum  grande  Say 
Argiope  trifasciata  Fors. 
Formica  cinerea  var.  neocinerea  Wheeler 
Orphulella  speciosa  Scud. 
Orchelimum  vulgare  Harr. 
Xiphidium  strictum  Scud. 
Stenobothrus  curlipennis  Harr. 
Conocephalus  ensiger  Harr. 
Scudderia  texensis  S.  and  P. 
Alhysanus  slriolus  Fall. 
Agallia  4-punctata  Prov. 
Platymetopius  actitus  Say 
Trigonotylus  ruficornis  Four. 
Miris  dolabrata  Linn. 
Chlorotettix  spatulata  O.  and  B. 
Sticlocephala  lutea  Wlk. 
Halticus  uhleri  Giar. 
Euschishis  variolarius  Pal.  Beauv. 
Plagiognathus  polilus  Uhl. 
i^Eutettix  stratninea  Osb. 
Empoasca  mali  LeB. 
Thyreocoris  pulicaria  Van  D. 
Alydus  cons  per  sus  Mont. 
Cosmopepla  carnifex  Fab. 
Gargamis  fusiformis  Say 
Horcias  marginalis  Reut. 
M ordellislena  connata  Lee. 
Cycloneda  sanguinea  muttda  Say 
Pachybrackys  sp. 

Typophorus  canellus  gilvipes  Horn 
Photinus  punctulatus  Lee. 
Eristalis  tenax  Linn. 
Liopellis  vernalis  Harlan 


CHAPTER  XV 
GENERAL  DISCUSSION      - 
I.    Introduction 

We  have  briefly  presented  some  facts  regarding  the  nature  and 
environmental  relations  of  animals,  an  account  of  the  environment,  and 
a  discussion  of  the  inhabitants  of  some  of  the  tjpe  habitats  of  the  forest 
and  forest  border  regions.  We  noted  also  in  preceding  chapters  sorne 
aspect  of  relations  of  the  animals  of  the  same  and  of  different  com- 
munities to  one  another,  and  our  relations  to  them.  We  may  still 
present  (a)  the  relations  of  the  different  communities  to  one  another, 
(b)  the  laws  governing  distribution,  and  (c)  a  discussion  of  the  relations 
of  ecology  to  broader  geographic  problems. 

II.    Application  of  the  Laws  Governing  Animal  Activities  to 
World  and  Regional  Problems 

As  was  stated  in  the  first  chapter,  the  relative  importance  of  different 
environmental  factors  is  not  definitely  known,  but  probably  in  local  and 
experimental  conditions,  land  environments  can  best  be  measured  in 
terms  of  evaporating  power  of  the  air,  light,  and  materials  for  abode, 
aquatic  environment  by  carbon  dioxide,  oxygen,  and  materials  for  abode. 
In  explaining  extensive  or  regional  distribution,  a  few  factors  have 
been  emphasized  and  these  usually  in  the  sense  of  barriers.  Merriam 
(48)  emphasizes  temperature,  Walker  (128)  atmospheric  moisture. 
Heilprin  (192,  p.  39),  like  most  paleontologists,  emphasizes  food. 
Nothing  is,  I  believe,  more  incorrect  than  the  idea  that  the  same  single 
factor  governs  the  regional  distribution  of  most  animal  species.  Since 
the  environment  is  a  complex  of  many  factors,  every  animal,  while  in 
its  normal  en\aronmental  complex,  lives  surrounded  by  and  responds 
to  a  complex  of  factors  in  its  normal  activities  (44,  p.  193).  Can  a 
single  factor  control  distribution? 

I.    reactions  to  single  factors 
Considerable  physiological  study  of  organisms  has  been  conducted 
with  particular  reference  to  the  analysis  of  the  organism  itself,  but  with 
little  reference  to  natural  environments.     Many  of  the  factors  and  con- 
ditions employed  in  such  experiments  are  of  such  a  nature  that  the 

299 


300  ECOLOGY 

animal  would  rarely  or  never  encounter  them  in  its  normal  life.  Other 
experiments  are  attempts  to  keep  the  environment  normal,  except  for 
one  factor  (44,  p.  180).  These  have  demonstrated  that  animals  are 
capable  of  responding  to  the  action  of  a  single  stimulus. 

A  typical  experiment  to  demonstrate  this  would  consist  in  preparing 
two  long  receptacles  in  such  a  way  that  one  is  the  normal  environment 
of  the  animals  in  all  respects  and  the  other  in  all  respects  except  for 
one  factor,  as,  for  example,  temperature.  The  temperature  conditions 
of  the  latter  might  be  as  follows:  temperature  at  one  end  10°  C,  at  the 
other  35°  C,  with  a  gradient  between.  If  then  100  animals  are  placed 
in  each  of  the  receptacles,  those  placed  in  one  end  of  the  gradient  will 
soon  show  signs  of  stimulation  and  will  move  about  until  they  corhe 
near  the  center  of  the  pan  where  the  temperature  is  2o°-25°.  If,  after 
sufficient  time  has  elapsed  for  the  experimental  animals  to  take  up  this 
position,  the  control  animals  have  remained  equally  distributed,  the 
experiment  will  show  that  the  animals  have  responded  to  temperature 
alone. 

Certain  general  laws  govern  the  reaction  of  animals  to  different 
intensity  of  the  same  stimulus.  Take,  for  example,  temperature. 
There  is  in  most  animals  which  have  been  subjected  to  experimentation 
with  temperature  a  range  of  several  degrees  within  which  the  activities 
of  the  animal  proceed  without  marked  stimulative  features,  as  is  sug- 
gested by  the  experiment  outlined  above.  Conditions  within  this 
range  of  several  degrees  are  called  the  optimum.  As  the  temperature 
is  raised  or  lowered  from  such  a  condition,  the  animal  is  stimulated. 
If  the  temperature  is  continuously  raised,  a  point  is  reached  at  which 
the  animal  dies.  The  temperature  condition  just  before  death  occurs 
is  called  the  maximum  (35).  The  lowering  of  temperature  produces 
comparable  results, 

2.      EXPERIMENTAL   STUDIES   OF  HABITAT   SELECTION 

Animals  select  their  habitats,  and  distribution  is  the  result  of  this 
selection.  To  decide  whether  or  not  one  factor  can  determine  distri- 
bution, experiments,  of  which  the  following  is  a  typical  example,  have 
been  performed. 

a)  Methods  of  experimentation. — Do  animals  select  their  breeding- 
places  ?  To  answer  this  question,  tiger-beetles  were  selected  as  material 
and  adults  were  placed  in  cages  containing  soil  of  several  kinds.  Each 
kind  was  so  arranged  into  steep  and  level  parts,  that  about  one  square 
foot  of  each  type  was  exposed.    The  adults  placed  in  the  cage  were 


ACTIVITY  AND  DISTRIBUTION 


301 


taken  when  the  species  was  breeding  (see  p.  212).  The  soil  was  kept  very 
moist  up  to  the  time  the  first  ovipositor  holes  were  made,  because  this 
species  lays  only  in  moist  soil.  After  this  the  wetting  of  the  soil  was 
done  very  cautiously,  so  as  not  to  wash  the  eggs  from  the  ground  in 
steep  parts.  Accordingly,  the  holes  were  not  obliterated  from  day  to 
day.  The  counts,  however,  are  not  accurate  for  the  soil  in  which  a  large 
number  were  made,  because  eggs  are  sometimes  laid  very  close  together 
and  adjoining  holes  destroyed.  Some  eggs  are  deposited  in  irregular 
cracks  and  crevices  where  they  are  likely  to  be  overlooked.  The  greatest 
care  was  taken  to  discover  every  hole  made  in  the  soils  in  which  larvae 
do  not  occur  in  nature.  Soils  in  the  different  lots  were  arranged  in 
different  orders. 

h)  Results. — Table  LXVIII  shows  the  approximate  number  of  holes 
made  in  the  clay  and  probably  the  actual  number  made  in  the  other 
soils,  together  with  the  number  of  larvae  which  appeared:  80  per  cent 
on  the  steep  slope,  98  per  cent  in  clay. 

The  count  of  holes  includes  some  in  the  first  stages  of  digging,  mere 
scratches  on  the  ground,  and  others  which  had  been  excavated  to  the 
usual  depth  with  or  without  eggs  being  laid. 

TABLE  LXVIII  (55) 

Distribution  of  Ovipositor  Holes  and  Larvae  of  C.  purpurea  limbalis  under 
Experimental  Conditions 
S  =  steep;  L  =  level. 


Clay 

Clay,  q  Pts. 
Humus,  i  Pt. 

Forest 
Humus 

Humus,  i  Pt. 
Sand,  9  Pts. 

Clean 

Sand 

S 

L 

S 

L 

S 

L 

S 

L 

S 

L 

^-i  {S?ae::;::: 
i-°'n{Ho'?„;:;::: 

L°'ni{«*-:;::: 

0 

9 
21 
12 

17 
24 

0 
0 

S 

I 

7 
10 

0 

0 
0 
0 
0 
0 

0 
0 
0 
0 
0 
0 

0 
0 
c 
0 
0 
0 

0 
0 
0 
0 

0 
0 

0 

0 
0 
0 
0 
0 

0 
0 
0 
0 
0 
0 

0 
0 
0 
0 
0 
0 

0 
0 
0 
0 
0 
0 

c)  Factors  controlling  habitat  selection  (55). — Pairs  taken  in  coitus 
were  placed  in  cages  containing  sand  only  and  level  clay  only.  No 
larvae  appeared  in  either  case.  The  experiment  with  the  level  clay 
has  not  been  repeated.  Females  placed  in  cages  containing  rough, 
steep  clay,  deposited  eggs.  Eggs  are  also  absent  from  dry  soils,  whether 
steep  or  level. 


302 


ECOLOGY 


Slope,  kind  of  soil,  and  soil  moisture  are  factors  governing  the 
deficiency  or  absence  of  eggs.  A  deficiency  or  excess  in  any  one  of 
these  respects  decreases  the  number  of  eggs  laid,  or  causes  them  not  to 
be  laid  at  all.  The  animals  are  in  the  condition  for  egg-laying  for  but  a 
short  period. 

d)  Method  of  selection. — It  has  been  determined  by  opening  holes 
that  eggs  are  not  laid  in  all,  and  in  one  case  the  first  holes  made  by  the 
female  were  empty.  This  would  tend  to  show  that  the  female  beetle 
tries  the  soil  before  laying  the  eggs,  but  I  have  not  been  able  in  other 
cases  to  determine  whether  the  first  holes  contained  eggs  or  not.  To 
determine  this,  it  would  be  necessary  to  watch  a  female  all  of  the  time 
during  several  days, 

3.      LAW   OF   TOLERATION    (55) 

Repeated  experiments  with  several  species  have  shown  results 
similar  to  those  shown  in  Table  LXVIII,  and  we  have  concluded  that  the 
egg-laying  place  of  the  tiger-beetles  is  their  true  habitat.  The  tiger- 
beetles  which  lay  eggs  in  soil  do  so  only  when  the  surrounding  tempera- 
ture and  light  are  both  suitable,  the  soil  moist  and  probably  also  warm. 
The  soil  must  satisfy  the  ovipositor  (egg-laying  organ)  tests  with  respect 
to  several  factors.  Egg-laying,  the  positive  reaction,  is  then  probably 
a  response  to  several  factors.  Furthermore,  after  the  eggs  are  laid,  the 
conditions  favorable  for  egg-laying  must  continue  for  about  two  weeks 
if  the  eggs  are  to  hatch  and  the  larvae  reach  the  surface.  The  success 
of  reproduction  depends  upon  the  quahtative  and  quantitative  com- 
pleteness of  the  complex  of  conditions.  This  complete  complex  is  called 
the  ecological  optimum.  The  negative  reaction,  on  the  other  hand,  appears 
to  be  different.  The  absence  of  eggs,  the  number  of  failures  to  lay,  and 
therefore  the  number  of  eggs  laid  in  any  situation,  can  be  controlled  by 
qualitative  or  quantitative  conditions  with  respect  to  any  one  of  several 
factors.  The  presence,  absence,  or  number  of  eggs  laid  may  be  governed 
by  a  single  factor. 

For  example,  all  other  conditions  being  optimum,  moisture  may 
control  the  presence,  absence,  or  number  of  eggs  laid.  If  the  moisture 
be  optimum,  the  maximum  number  of  eggs  will  be  laid.  If  it  is  too 
great  few  or  no  eggs  will  be  laid.  This  factor  then  controls  according 
as  it  is  near  the  optimum,  or  near  either  the  maximum  or  minimum 
tolerated  by  the  species.  It  is,  however,  not  necessary  that  but  a  single 
factor  should  deviate ;  the  effect  is  similar  or  more  pronounced  if  several 
vary. 


LAW  OF  TOLERATION  303 

The  success  of  a  species,  its  numbers,  sometimes  its  size,  etc.,  are 
determined  largely  by  the  degree  of  deviation  of  a  single  factor  (or 
factors)  from  the  range  of  optimum  of  the  species.     It  is  obvious  that 
the  cause  of  the  fluctuation  might  be,  for  example,  moisture  due  to 
(climatic)  deficiency  in  rainfall,  or  rapid  run-ofif,  due  to  steep  slope. 
The  evidence  for  the  application  of  the  law  of  toleration  to  local  distribu- 
tion is  good.     Since  the  same  factors  are  involved  in  the  "geographic" 
or  more  extensive  distribution,  there  is  no  difficulty  in  the  application 
of  the  law  to  such  distribution  also,  for,  to  assume  that  the  law  is  not 
applicable  is  to  assume  that  animals  distinguish  between  the  causes 
which  lie  back  of  the  changes  in  physical  factors  by  which  they  are  affected. 
The  fact  that,  in  so  far  as  our  observation  can  go  at  present,  most  animals 
are  found  in  similar  conditions  throughout  their  ranges  is  also  good 
evidence  for  the  application  of  both  the  laws  of  minimum  and  toleration 
to  problems  of  geographic  range.     In  fact,  the  law  of  minimum  (see  p.  68) 
is  but  a  special  case  of  the  law  of  toleration.     Combinations  of  the  factors 
which  fall  under  the  law  of  minimum  may  be  made,  which  make  the  law 
of  toleration  apply  quite  generally.     For  example,  food  and  excretory 
products  may  be  taken  together  as  constituting  a  single  factor.     From 
this  point  of  view  the  law  of  toleration  applies,  the  food  acting  on  the 
minimum  side,  excretory  products  on  the  maximum. 

4.      APPLICATION   OF   THE   LAW   OF   TOLERATION   TO   DISTRIBUTION    (55) 

As  has  already  been  implied,  the  locality  or  region  of  optimum,  or 
the  locality  or  region  in  which  the  animal  is  most  nearly  in  physiological 
equilibrium,  is  called  the  habitat  (ecological  optimum)  when  it  refers 
to  ecological  or  local  distribution,  and  the  center  of  distribution  when  it 
refers  to  extensive  areas.  The  so-called  centers  of  distribution  are 
often  only  areas  in  which  conditions  are  optimum  for  a  considerable 
number  of  species.  The  distribution  and  number  of  individuals  of  any 
species  may  be  graphically  represented  as  below: 

Minimum  Limit  of 


Toleration 


Absent 


Decreasing 


Range  of  Optimum 


Habitat  or  center  of  distribution 
Greatest  abundance 


Maximum  Limit  of 
Toleration 


Decreasing 


Absent 


On  account  of  the  nature  and  distribution  of  climatic  and  vegetational 
conditions,  it  follows  that  as  we  pass  in  one  direction  from  a  center,  one 
factor  may  fluctuate  beyond  the  range  of  toleration  of  a  species  under 
consideration;  but  as  we  pass  in  another  direction  the  fluctuating 
factor  is  very  likely  to  be  different. 


304  ECOLOGY 

a)  Governing  the  limit  of  local  and  geographic  range. — The  geographic 
or  local  range  of  any  species  is  limited  by  the  fluctuation  of  a  single 
factor  (or  factors)  beyond  the  limit  tolerated  by  that  species.  In  non- 
migratory  species  the  limitations  are  with  reference  to  the  activity  which 
takes  place  within  the  narrowest  limits  (usually  breeding).  In  migratory 
species  this  activity  limits  the  range  during  only  a  part  of  the  life  history. 

b)  Governing  the  distribution  area  and  habitat  area  (55). — ^The  dis- 
tribution area  of  a  species  is  the  distribution  of  the  complete  environ- 
mental complex  in  which  it  can  live,  as  determined  (i)  by  the  activity 
which  takes  place  within  the  narrowest  limits  and  the  animal's  power 
of  migration,  and  (2)  by  barriers  in  which  some  factor  of  the  complex 
fluctuates  beyond  the  limits  of  toleration  of  the  species  in  all  periods  of 
its  life  history. 

If  these  statements  are  borne  out  by  further  investigation  it  follows 
that  every  study  of  animal  behavior  which  is  related  to  measured  physical 
factors  or  to  natural  environments  is  directly  related  to  problems  of  dis- 
tribution. 

III.    Agreement  between  Plants  and  Animals 

In  recent  years  the  ecology  of  plants  has  received  much  attention 
and  the  subject  has  made  great  progress.  In  animal  ecology  but  little 
progress  has  been  made,  and  students  (and  teachers)  have  been  inclined 
to  expect  relations  and  conditions  in  animals  parallel  with  those  in  plants. 
Little  progress  has  been  made,  largely  because  workers  have  not  recog- 
nized the  important  phenomena  in  animals  as  compared  with  plants. 

.     I.      ECOLOGICAL  AGREEMENT   OF  INDIVIDUALS 

Organisms  may  be  divided  on  the  basis  of  their  ability  to  move 
about,  into  sessile  or  fixed,  and  motile  forms.  All  organisms  are  of  course 
capable  of  movement  of  some  sort,  even  though  it  be  only  mechanical 
movement  dependent  upon  turgor.  There  are  also  all  degrees  of  ability 
to  move  from  place  to  place.  Some  motile  plants  and  animals  move 
about  only  very  slowly,  and  the  division  of  organisms  into  sessile  and 
motile  is  a  somewhat  artificial  classification,  as  many  forms  are  difl5cult 
to  place  in  either  group.  Some  are  sessile  at  one  period  of  their  lives 
and  motile  at  another.  Comparable  difficulty  arises,  however,  in  the 
separation  of  plants  from  animals. 

The  animals  with  which  we,  as  inland  people,  are  most  familiar, 
are  the  highly  motile  forms,  and  the  plants  with  which  we  are  most 
familiar  are  sessile  forms.     We  are  all  also  somewhat  familiar  with 


AGREEMENT  OF  COMMUNITIES  305 

numerous  marine  animals,  such  as  polyps,  sea  plumes,  etc.,  which  are 
sessile,  like  plants.  Sessile  animals  are  probably  all  aquatic.  Logically, 
ecology  cannot  be  divided  into  plant  and  animal  ecology,  but  it  may  be 
divided  into  the  ecology  of  sessile  and  motile  organisms. 

An  appreciation  of  the  likenesses  and   differences  of  sessile  and 

motile  organisms  is  an  important  thing  in  ecology.     The  plant  and  the 

animal  groups  contain  both  sessile  and  motile  types  together  with  types 

intermediate  between  the  two  and  thus  taken  as  a  whole  plants  and 

animals  are  in  agreement  in  the  matter  of  response.     However,  since  the 

vast  majority  of  animals  with  which  we  deal  are  motile,  their  activities 

are  evident  because  of  their  ability  to  move  about.     On  the  other  hand 

the  majority  of  plants  are  sessile,  and  sessile  individuals  usually  can 

change  the  position  of  the  whole  or  its  parts  only  by  growth.     Changes 

in  the  relation  and  character  of  parts  are  the  results  of  the  application  of 

stimuli  to  sessile  plants.     Movement  is  the  chief  result  of  the  application 

of  stimuli  to  animals.     Animal  ecology  has  very  much  in  common  with 

plant  ecology.     Diatoms,  fiatworms,  and  many  other  marine  animals 

and  plants  meet  the  same  conditions  in  the  same  or  similar  ways  (72, 

P-  121;   53a,  p.  156;   53^  P-  155)-     Sessile  animals,  such  as  reef-forming 

corals,  show  growth  form  differences  (193,   194,   195)  under  different 

conditions,  just  as  sessile  plants  do.     Comparable  plants  and  animals 

show  comparable  responses.     The  physiological  life  history  aspect  of 

plant  ecology  (52)  is  parallel  with  the  same  phenomenon  in  animals, 

but  the  activities  of  motile  animals  correspond  roughly  to  the  growth 

form  phenomena  in  sessile  plants  (55,  p.  593). 

All  the  way  through  the  study  of  ecology  we  look  for  behavior  or 
activity  difference  in  motile  organisms  (chiefly  animals),  when  con- 
sidering the  species  of  two  different  habitats,  while,  when  making  a 
comparison  of  the  sessile  organisms  (chiefly  plants)  of  two  habitats, 
we  look  for  differences  in  form  and  structure.  To  be  sure  an  occasional 
sessile  plant  can  move  some  of  its  parts  and  likewise  some  motile  animals 
change  color,  size,  or  form  with  differing  conditions  during  development, 
but  these  are  of  secondary  rather  than  primary  importance  and  we  must 
look  mainly  to  form  changes  as  ''plant  response''  and  behavior,  or  activity 
changes  as  "animal  response.'' 

2.      AGREEMENT   OF   COMMUNITIES 

Are  physical  conditions  sometimes  similar  when  vegetation  and 
landscape  aspect  are  very  different  ?  That  they  are  is  clearly  suggested 
when  we  compare  the  forest  and  the  shrub-covered  bluff  where  forest 


306  ECOLOGY 

animals  occur.  Plants  grow  from  seeds  only  under  a  very  limited  range 
of  conditions.  However,  if  trees  are  given  a  few  years'  growth  under 
favorable  conditions  they  will  be  successful  under  a  great  range  of  con- 
ditions. The  great  age  to  which  trees  often  live  and  the  slowness  with 
which  they  grow  make  it  possible  for  conditions  to  change  while  the 
trees  still  live  on  with  changes  only  in  leaf  structure.  It  is  to  be  expected 
that  the  distribution  of  animals  is  correlated  with  the  occurrence  of 
seedlings  or  of  quick-growing  plants  or  at  least  with  leaf  structure  tj-pes 
rather  than  strictly  with  species  of  trees.  These  facts  suggest  that 
there  are  two  types  of  cases  in  which  physical  conditions  and  forest 
conditions  are  not  in  accord.  In  the  first  case  atmospheric  conditions 
become  favorable  for  forest  animals  before  any  woody  plants  have  been 
able  to  grow;  in  the  second,  woody  plants  remain  after  conditions  have 
become  unfavorable  for  forest  animals;  both  are  due  to  lagging  behind 
of  vegetation;  both  are  very  local  and  of  minor  significance. 

The  reasons  for  the  wide  distribution  of  some  animals  in  the  forest 
stages  which  we  have  considered  are  no  doubt  vaiious.  For  example 
Zonitoides  arboreus  (Table  L,  p.  252)  is  rare  in  the  early  stages  and  is 
confined  to  the  lower  and  moister  localities.  If  Epeira  domicilorum  is  a 
species  of  stable  physiological  makeup  we  can  offer  no  explanation  for 
its  peculiar  distribution  (Table  LVI,  p.  257).  A  species  may  have  its 
critical  period  in  the  early  spring  when  the  leaves  are  off  the  trees  and 
the  condition  of  the  atmosphere  similar  in  all  stages  (see  Fig.  251,  p.  248) 
or  may  live  at  higher  levels  in  the  denser  and  older  stages,  and  thus  be 
surrounded  by  similar  atmospheric  conditions,  but  we  are  not  warranted 
in  assuming  either  of  these  causes  here. 

Another  striking  feature  of  the  distribution  of  many  beetles,  bugs, 
spiders,  and  Orthoplera  is  the  fact  that  they  are  found  in  open  woods, 
edges  of  woods,  on  the  vegetation  of  marshes,  and  over  the  water  of  small 
ponds  in  which  vegetation  is  growing.  In  this  way  many  species  are 
found  to  occur  in  what  at  first  appear  to  be  very  unlike  situations. 
Lygus  pratensis,  Triphleps  insiduosus,  and  Euschustus  variolarius, 
which  occur  on  the  vegetation  of  the  margins  of  swamps,  of  the 
black-oak  forest  dunes,  and  on  prairies  and  agricultural  lands,  may 
serve  as  examples.  Shull  has  pointed  out  similar  facts  as  one  of  the 
difficulties  in  the  way  of  ecological  classification  of  Orthoptera  and 
Thysanoptera.  Such  species  as  the  bugs  mentioned  above  are  said  to 
occur  "everywhere,"  although  they  are  rarely  found  in  moist  woods  or 
in  any  situation  in  which  they  are  not  fully  exposed  to  the  sun  and 
may  always  live  in  similar  conditions. 


AGREEMENT  OF  COMMUNITIES 


307 


Some  investigators  have  questioned  the  importance  of  vegetation 
to  animals  and  we  note  here  that  the  distributions  of  plant  and  animal 
species  are  not  always  correlated.  If  one  refers  to  species  of  plants 
and  species  oi  animals  then  the  vegetation  very  often  is  not  correlated 
with  the  distribution  of  the  animals.  If  on  the  other  hand  one  means 
that  the  plants  are  controllers  of  physical  conditions,  then  vegetation 
can  be  said  to  be  of  very  great  importance. 

Before  discussing  the  problem  of  agreement  between  plant  and 
animal  communities,  it  is  necessary  to  state  what  is  meant  by  agreement. 
According  to  present  developments  of  the  science  of  ecology  plant  and 
animal  communities  may  be  said  to  be  in  full  agreement  when  the  growth 
form  of  each  stratum  of  the  plant  community  is  correlated  with  the  conditions 
selected  by  the  animals  of  that  stratum.  Questions  of  agreement  are  pri- 
marily questions  for  experimental  solution.  Two  types  of  disagreement 
are  to  be  expected.  We  may  illustrate  the  first  by  a  bog  or  marsh 
community.  Considering  plants  rooted  in  the  soil  we  note  that  water 
is  secured  from  the  soil  by  the  roots  and  is  lost  through  the  leaves  and 
twigs.  Accordingly  since  bog  soil  is  unfavorable,  due  to  the  presence 
of  toxins  or  to  other  causes,  plants  growing  in  it  do  not  secure  water 
easily  even  when  the  quantity  of  soil  water  is  great.  Such  plants  have 
xerophytic  structures  (which  tend  to  check  the  loss  of  water)  developed  far 
beyoiui  the  requiretnents  of  the  atmospheric  coruiitions  surrounding  their 
vegetative  parts.  It  is  improbable  that  the  animals  inhabiting  a  bog- 
vegetation  field  stratum  would  select  atmospheric  conditions  such  as 
produce  equally  xerophytic  structures  under  favorable  soil  conditions. 
We  may  therefore  expect  disagreement.  The  smaller  plants  such  as 
fungi,  algae,  etc.,  are  related  to  the  strata  of  soil  and  atmosphere  exactly 
as  the  smaller  animals  and  as  much  disagreement  is  to  be  expected  between 
such  plants  and  the  rooted  vegetation  as  between  the  rooted  vegetation 
and  animals.  It  must  also  be  noted  that  the  xerophytic  structures  of 
the  plants  of  unfavorable  soils  may  have  important  influence  upon  ecto- 
phytic  plants  and  animals  and  in  part  counteract  the  effect  of  favorable 
atmospheric  conditions. 

The  second  type  of  disagreement  is  represented  by  cases  in  which 
the  vegetation  lags  behind.  We  have  already  noted  that  on  the  clay 
bluff  pp.  209-(i7)  conditions  become  favorable  for  inconspicuous  plants 
and  forest  animals  as  soon  as  the  growth  of  the  pioneer  vegetation  gives 
shade  to  the  soil.  In  other  cases  woody  vegetation  remains  in  situations 
where  the  conditions  have  become  unfavorable  for  it  and  the  less  con- 
spicuous plants  and  some  of  the  animals  have  disappeared.     We  may 


3o8  ECOLOGY 

expect  lack  of  accord  within  and  between  plant  and  animal  communities 
under  such  conditions.  In  these  cases,  however,  conditions  are  only 
temporarily  out  of  adjustment,  due  to  rapid  physiographic  changes,  and 
we  note  from  the  data  presented  that  plant  and  animal  communities 
are  usually  in  agreement.  The  exceptions  are  often  apparent  only  and 
due  to  the  emphasis  of  species  instead  of  mores  and  growth  form.  From 
this  viewpoint  and  with  such  exceptions  as  are  noted,  plant  and  animal 
communities  are  probably  in  agreement  the  world  over. 


IV.    Relations  of  Communities 

I.      succession — CAUSES 

Succession  is  no  doubt  one  of  the  most  important  and  widespread 
of  the  phenomena  discovered  by  the  ecologists  up  to  the  present  time 
(120, 197).  Simply  stated,  it  means  that  on  a  given  fixed  area  organisms 
succeed  one  another,  because  of  changes  in  conditions.  These  changes 
make  impossible  the  continued  existence  of  the  forms  present  at  any 
given  time;  with  the  death  or  migration  of  such  forms,  others  adapted  to 
the  changed  conditions  occupy  the  area,  whenever  such  adapted  forms 
are  available.  The  changes  referred  to  result  from  physical  or  bio- 
logical causes,  or  combinations  of  the  two.  It  is  probable  that  the  causes 
of  the  changes  are  frequently  complex  combinations  of  various  factors. 

We  have  among  the  physical  causes  changes  in  climate  and  changes 
in  topography.  All  degradation  of  land  is  a  cause  of  succession.  Such 
geological  processes  are  well  understood  and  treated  in  textbooks  on 
geology  and  physiography. 

The  biological  causes  of  succession  lie  chiefly  in  the  fact  that  organ- 
isms frequently  so  affect  their  environments  that  neither  they  themselves 
nor  their  offspring  can  continue  to  live  at  the  point  where  they  are  now 
living.  Every  organism  adds  certain  poisonous  substances  to  its  sur- 
roundings, and  takes  away  certain  substances  needed  by  itself.  It 
frequently  thus  so  changes  conditions  that  its  offspring  cannot  live  and 
grow  to  maturity  in  the  same  locality  as  the  parents.  However,  by 
these  same  processes  it  prepares  the  way  for  other  organisms  which  can 
live  and  grow  in  the  conditions  thus  produced. 

Obviously,  those  organisms  whose  decaying  bodies  and  excretory 
materials  are  not  removed  or  distributed  by  their  wanderings  will 
modify  their  environments  most.  Organisms  which  remain  in  one 
place  do  nothing  which  tends  to  remove  the  results  of  their  own  existence, 
and  frequently  modify  their  environments  in  manners  detrimental  to 


CONVERGENCE  309 

themselves."  On  the  land,  plants  are  the  dominant  sessile  forms,  and 
often  profoundly  modify  the  conditions  in  which  they  live,  so  that  they 
cannot  succeed  themselves.  When  will  the  process  of  succession  stop  ? 
Obviously,  it  must  cease  when  there  are  no  available  species  to  take  the 
places  of  those  which  have  destroyed  their  own  habitats.  There  are 
species  which  are  immune  to  their  own  products  and  the  products  of  the 
species  which  are  associated  with  them.  Obviously,  when  a  condition 
in  which  these  species  can  live  is  reached,  and  they  come  to  occupy  the 
place  which  is  thus  made  ready  for  them,  the  formation  which  they 
constitute  can,  so  far  as  the  plants  are  concerned,  last  indefinitely.  This 
is  theoretically  true  of  all  climax  or  geographic  formations,  and  has  been 
established  for  the  beech  and  maple  forest  of  eastern  America. 

2.      MOTILE    AND   SESSILE    ORGANISMS   IN   SUCCESSION 

Motile  Organisms  Fixed  Organisms 

o)  Motile  organisms  affect  their  own  a)  Sessile    organisms    modify    their 

environments  by  the  destruction  own  environments  largely  through 

of  materials  of   abode   and   food  growth  of  their  own  bodies,  cutting 

supply  and  the  pollution  of  their  off  light,  interfering  with  circula- 

habitats  by  waste  products  (196,  tion  in  surrounding  medium  and 

114,  and  citations).  accumulation   of   waste   products 

(195,  120). 

b)  The  changes  under  {a)  make  the  h)   The  same  as  for  motile  organisms 
•  continued  existence  of  the  group  (197). 

in  question  impossible  and  pre- 
pare the  way  for  other  differently 
adapted  (succession)  forms. 

c)  Succession    is    a    succession    of      c)   Breeding  and  living  places  are  not 
breeding-places.  contrasted  as  young  stages  usually 

thrive  only  where  adults  can  live. 
Succession  can  take  place  only  where  forms  adapted  to  the  changed 
conditions  are  available. 

3.   CONVERGENCE 

The  work  of  running  water,  for  example,  is  in  a  measure  convergent. 
When  a  new  body  of  land  is  uplifted,  streams  begin  to  work  their  way 
into  the  new  land  mass  and  cut  deep  valleys.  The  formation  of  numer- 
ous tributaries  (92  and  citations)  isolates  portions  of  the  upland  in  the 

'  In  the  sea  (195)  sessile  forms  are  chiefly  animals  and  animals  are  probably  the 
chief  cause  of  succession  there.  Coral  polyps  cannot  build  upward  indefinitely,  as 
they  soon  reach  the  surface  and  can  no  longer  exist.  By  reaching  the  surface  they 
prepare  the  way  for  other  forms. 


3IO 

SAND  RIDGE 
Cottonwood 
Gray  pine 
Black  oak 

White  oak 
Red  oak 


ECOLOGY 


CLAY  BLUFF 
Aspen 
Cottonwood 
Hop-Hornbeam 
White  oak 
Red  oak 


Hickory         Hickory 

BEECH  AND  SUGAR  MAPLE 

Tulip  Hickory 

Basswood  Red  oak 


White  elm  and 
White  ash 

Swamp  white  oak 
Buttonbush 
Cattail  and  Bulrush 


Water-lily  and  Water 
Mill-foil 


Bur  oak 

Basswood 
Hawthorn 


Slippery  elm  and 
White  elm 


Chara 


POND 


River  maple 
Black  willow 
FLOOD-PLAIN 


Diagram  8. — Showing  the  convergence  of  four  types  of  habitat,  to  the  beech 
and  maple  forest.  Read  from  the  extremities  toward  center.  (Prepared  with  the 
assistance  of  Dr.  Cowles  and  from  his  writings.) 


CLIMATIC  COMMUNITIES  311 

form  of  hills.  These  hills  are  broken  up  into  smaller  hills  by  the  smaller 
tributaries,  and  the  resulting  hills  into  still  smaller  ones,  until  the  upland 
is  all  removed  and  the  country  reduced  to  a  generally  level  condition 
known  as  a  peneplain.  The  process  of  penepianation  then  tends  to 
fill  all  low  lakes  and  ponds  and  drain  all  high  ones.  It  works  over  all  the 
materials  of  the  upland  and  lays  them  down  as  alluvial  deposits,  Avhich 
process  tends  to  make  the  surface  materials  of  a  uniform  nature.  Asso- 
ciated with  this,  and  more  or  less  independent  of  it,  the  process  of  plant 
succession  makes  the  conditions  coverging  (Diagram  8)  to  a  still  greater 
degree  (13). 

The  principle  of  convergence,  while  not  generally  established,  is 
believed  to  be  of  wide  application.  It  has  been  suggested  for  the  tropical 
forest  of  the  Philippines  by  Whitford  (198),  for  the  coniferous  forest 
regions  of  North  America  by  Adams  and  by  Gleason,  and  for  the  arid 
Southwest  by  Ruthven.  Theoretically  at  least,  in  all  the  varied  types  of 
land  habitats  of  any  large  area,  communities  are  tending  toward  some 
one  tv-pe  which  is  primarily  adjusted  to  the  climate  of  the  region  when  its 
topography  approaches  base  level.  Such  a  climatic  type  of  community 
rapidly  displaces  the  communities  of  all  the  varied  kinds  of  soil  of  a 
newly  uplifted  area  which  is  only  a  few  hundred  feet  above  the  sea.  In 
these  situations  the  climatic  communities  dominate  sterile  soil  by  process 
of  successional  development  extending  over  a  few  score  or  hundreds  of 
vears. 


V.     General  Relation  of  Communities  of  the  Same 
Climate  (13) 

In  each  climatic  realm  of  the  world  there  are  relations  between 
communities  of  two  sorts,  (a)  physiological  relations,  best  defined  as 
physiological  similarities,  and  (Z>)  successional  or  evolutionary  relations. 
Diagram  9  shows  both  types  of  relations  for  the  temperate  American 
forest  border  area.  Single-pointed  arrows  show  the  directions  of  suc- 
cession, double-pointed  arrows  show  similarities  of  conditions  and  the 
occurrence  of  several  or  many  of  the  same  species  in  considerable  num- 
bers in  communities  between  which  such  arrows  extend.  Broken  lines 
indicate  less  definite  relations  than  the  solid  lines.  Starting  with  the 
aquatic  communities,  we  note  that  spring-fed  and  intermittent  stream 
communities  converge  with  physiographic  aging  to  small,  permanent, 
swift-stream  communities,  and  permanent  swift-stream  communities 
are  succeeded  by  base-level  stream  communities.     The  characteristic 


312 


ECOLOGY 


communities  of  small  permanent  streams  and  base-level  streams  are 
indicated  above.  Taking  up  another  line,  we  note  that  the  large-lake 
communities  are  succeeded  by  the  small-lake  communities.  Rocky- 
shore  communities  of  the  large-lake  areas  have  features  in  common  ^Yith 
those  of  the  rocky  rapids  of  the  stream.  The  sand,  gravel,  and  vegeta- 
tion communities  of  the  base-level  stream  and  the  small  lake  have  many 
things  in  common,  while  the  silt  and  humus  bottom  communities  are 
distinguishing  features  of  the  two.     Communities  of  ponds  originating 


SuKi 


.<^^ 


Rock 


Pond-^\(     iT  '  Climatic 

A      I  x^  ^'^^^^^Moisl  Forest  Margin-^Forest  Margin 

Sand  T  ►  \  egelation  "♦■•&, 

^^  Thickei-»— ''^•Thicket 


Base  Level    Stream- 
Sill  Bottom 


Spring  Fed  Brook— ^^' 


<i^ 


VV- 


.^' 


Diagram  9. — Showing  some  relations  of  the  chief  animal  communities  of  the 
forest-border  region  of  Central  North  America.  The  word  community  or  communi- 
ties is  to  be  understood  as  following  all  the  words  appearing  in  the  diagram.  For  full 
description  see  text. 


by  very  rapid  physiographic  changes  pass  through  a  series  of  stages 
comparable  to  those  found  in  the  different  parts  of  the  small  lake.  The 
lake  communities  pass  to  the  pond  community  stage  or  give  rise  to  a 
floating-bog  marsh  community  which  is  displaced  by  a  floating-bog 
thicket  community.  Cowles  states  that  this  takes  place  in  deep  lakes, 
while  the  shallow  ones  become  ponds  which  give  rise  to  marshes  with 
firm  substrata.  Such  a  marsh  community  may  be  displaced  wholly 
by  a  low  prairie  community,  in  part  by  a  thicket  forest  margin  com- 
munity, or  wholly  by  a  thicket  community  which  will  be  succeeded  by 


CORRESPONDENCE  OF  CLIMATIC  COMMUNITIES  313 

a  forest  community.  In  the  savanna  or  prairie  climate  the  marsh 
margin  thicket  may  become  a  climatic  thicket  or  forest  margin.  In  the 
savanna  or  prairie  climate  the  communities  of  all  the  various  soils  and 
the  low  prairie  community  may  converge  to  the  prairie  climate  com- 
munity, or  to  the  forest  community  as  is  shown  below  for  the  forest 
climate.  In  the  forest  climate  and  locally  in  the  savanna  climate  the 
communities  of  all  the  various  soils  pass  through  a  thicket  community 
stage  (T),  related  to  a  climatic  forest.  The  thicket  communities  of  all 
the  dry  soils  are  related  to  the  forest  margin  thicket  community  of  the 
savanna  climate. 

I.      CORRESPONDENCE   OF   COMMUNITIES   OF   DIFFERENT   PARTS   OF 
THE   WORLD    (55) 

The  botanists  have  abundant  evidence  for  the  correspondence  of 
the  formations  of  similar  climates  (58a).  The  vegetation  of  different 
parts  of  the  world  which  have  similar  climates  is  similar  and  the  plants 
though  usually  belonging  to  different  taxonomic  groups  are  similar  in 
growth,  form,  and  appearance.  Correspondence  and  similarity  of 
vegetation  is  not  limited  to  the  climatic  or  extensive  formations,  but 
applies  also  to  strictly  local  situations  wherever  the  physical  condiiions 
are  similar.  On  the  animal  side  we  have  less  trustworthy  evidence  of 
similarity  or  correspondence.  If  the  physiological  similarity  occurs  in 
the  same  community,  due,  as  has  just  been  stated,  to  selection  of  habitat 
and  modification  of  behavior,  we  conclude  that  it  occurs  in  all  communi- 
ties occupying  similar  conditions  and  that  similar  situations  in  different 
parts  of  the  world  have  physiologically  similar  communities,  and  identical 
situations  approximately  identical  communities. 

The  direct  evidences  for  the  correspondence  of  formations  in  different 
parts  of  the  world  are  as  follows:  {a)  the  existence  of  identical  or  closely 
corresponding  species  has  long  been  known  to  naturalists  (3,  199,  192); 
{b)  similarity  of  physiological  life  histories  of  many  species  is  well  known, 
as,  for  example,  corresponding  species  in  the  United  States  and  Europe 
or  Japan,  and  a  general  concentration  of  breeding  in  the  rainy  season  in 
all  arid  climates,  etc.;  {c)  certain  animals  in  similar  environments  in 
different  parts  of  the  world  appear  from  the  accounts  of  naturalists  to 
behave  alike  with  reference  to  the  physical  condition  of  different  parts 
of  the  day,  year,  and  different  weather.  P^or  example,  it  appears  that 
there  is  a  close  physiological  and  ecological  similarity  between  certain 
antelopes  of  the  savannas  of  Africa  and  certain  savanna  kangaroos  of 
Australia  (200).     In  other  words  certain  kangaroos  are  ecologically  and 


314  ECOLOGY 

physiologically  similar  to  some  antelopes.  As  has  already  been  stated, 
the  zoologist  is  usually  unduly  impressed  with  specificities  such  as  mode 
of  movement  of  limbs,  body,  etc.  Now  if  my  reader  pictures  an  African 
antelope  running  gracefully  from  a  pack  of  Cape  hunting  dogs  (102, 
pp.  119-23),  and  an  old-man-kangaroo  leaping  from  a  pack  of  dingoes 
(202,  pp.  41,  243),  noting  mainly  the  specific  peculiarities  of  the  movement 
of  limbs  and  body  of  the  pursued  in  each  case,  he  will  be  dwelling  upon 
specificities  of  little  ecological  significance  and  missing  the  point  of  view 
of  the  ecologist  altogether.  These  specificities  of  behavior  are  matters  of 
little  ecological  significance;  it  matters  not  if  one  animal  progresses  by 
sommersaults  so  long  as  the  two  are  in  agreement  in  the  matter  of  reac- 
tions to  physical  factors  as  indicated  by  the  manner  of  spending  the  day 
(200),  avoidance  of  forests,  swamps,  cold  mountain  tops,  etc.,  entirely 
available  to  them,  and  in  the  mode  of  meeting  enemies  as  indicated  by  the 
reaction  to  the  approaching  hunter  or  enemy. 

a)  Distribution  of  land  communities  represented  in  Central  North 
America. — The  following  climatic  formations  are  represented  at  Chicago 
and  distributed  as  given  below : 

Temperate  Deciduous  Forest  Formations:  Forest  with  broad,  thin  leaves  which 

are  shed  in  autumn;  near  Chicago,  oak,  hickory,  beech,  and  maple  (s8a). 

Distribution:    Eastern  North  America,  north  to  the  Great  Lakes; 

Chili,  north  to  35°;  Europe,  north  of  the  Alps,  and  south  of  60°; 

Japan  and  the  vicinity  of  Okhotsk  (580). 

Temperate  Savanna  Formations:    Grasslands  with  scattered  trees,  or  trees  in 

groves  surrounded  by  thickets,  and  with  dense  forests  along  larger  streams. 

Near  Chicago,  the  grassland  is  prairie  and  the  trees  chiefly  oak  and  hickory. 

Distribution:  A  narrow  belt  in  North  America  surrounding  the  great 

plains  on  the  east,  north,  and  west;  Uruguay,  South  Australia, 

South  Africa,  and  Eastern  Siberia. 

Formations  of  Forests  with  Narrow  Thick  Leaves:    Coniferous  forest.     Dense 

evergreen  forests  with  little  undergrowth.     Lies  just  to  the  north  of 

Chicago  and  was  represented  locally  in  the  parts  of  Michigan  shown  on 

Map  I  (frontispiece). 

Distribution:  North  America  north  of  the  Great  Lakes  and  Columbia 
River  extending  southward  into  the  mountains;  Eurasia  north 
of  60°,  extending  southward  into  the  mountains. 

The  localities  which  are  in  agreement  are  indicated  by  distribution 
of  the  different  t>^es  of  formation.  It  will  be  noted  that  the  deciduous 
forest  animal  formation  with  which  we  have  dealt  is  found  in  several 
parts  of  the  world,  this  animal  community  being  essentially  duplicated  in 


ECOLOGY  AND  BIOLOGY  315 

these  diflferently  located  areas.  This  correspondence  is  probably  much 
more  striking  physiologically  than  in  the  matters  of  interrelation  of 
species  because  in  some  formations  certain  groups,  as,  for  example, 
antelopes  in  African  steppes,  are  especially  numerous,  while  in  a 
corresponding  situation  in  South  America  they  are  very  few. 

As  has  already  been  suggested,  correspondence  is  not  limited  to 
the  gross  characters  of  extensive  formations,  but  is  equally  true  of 
the  more  local  communities.  In  matters  of  correspondence  of  species 
there  are  often  striking  correspondences  within  the  groups  of  formation 
indicated  above.  For  example,  there  is  a  striking  correspondence  in 
behavior  between  the  meerkats  of  the  steppes  of  East  Africa  (3)  and 
the  prairie  dogs  of  our  own  steppe,  both  being  grasslands  but  differ- 
ing in  climate.  Considering  a  local  formation,  as  that  of  the  sandy 
beaches  of  the  sea  and  very  large  lakes,  we  note  that  along  the  New 
England  coast  and  around  the  shores  of  Lake  Michigan  the  moist, 
sandy  beaches  are  inhabited  by  the  larvae  of  the  beach  tiger-beetle 
{Cicindela  hirticolUs)  (Fig.  134,  p.  179).  Along  the  Gulf  Coast  at  Galves- 
ton, Texas,  we  find  the  larvae  of  C.  saulcyi  inhabiting  almost  identical 
situations,  holes  of  about  the  same  depth,  etc.,  while  Dr.  Horn  (203) 
describes  a  different  larva  in  like  situations  and  with  like  habits  on  the 
coast  of  India. 

Still,  with  all  that  has  been  said,  matters  of  agreement  of  different 
animal  communities  in  different  parts  of  the  world  are  largely  theoretical, 
and  while  apparently  logically  well  grounded,  the  general  statement 
must  be  treated  with  due  caution  and  subjected  to  experimental  test 
as  soon  as  possible.  Such  testing  w^ill  involve  careful  experimental 
study  of  the  communities  of  two  like  environments  under  rigidly  con- 
trolled and  carefully  measured  conditions. 


VI.    Relations  of  Ecology  to  Other  Biological  Subjects 

The  environmental  processes  which  we  are  discussing  are  those  in 
which  organisms  have  existed  since  their  origin  on  earth.  The  stresses 
and  strains  to  which  organisms  have  been  subjected  have  been  in  the 
same  direction  for  long  periods.  Now  that  we  have  learned  much 
concerning  organic  response  to  en\dronment,  such  as  physiological 
response,  behavior  response,  and  structural  response,  we  note  at  once 
that  processes  of  adjustment  and  equilibration  of  living  substance  may 
bear  important  relations,  on  the  one  hand  to  environmental  processes, 
and  on  the  other  to  the  physiological  aspect  of  biological  phenomena. 


3l6  ECOLOGY 

Ecological  matters  are  then  worthy  of  the  attention  of  the  student  of 
morphology,  heredity,  and  evolution. 

What  is  the  significance  in  the  fact  that  the  white  tiger-beetle 
(Cicindela  lepida)  belongs  to  the  first  association  in  the  development 
of  a  forest  community  on  sand,  which  we  may  say  corresponds  to  a 
family,  and  to  the  subterranean  ground  stratum  (corresponding  to  genus) 
and  to  the  white  tiger-beetle  mores?  Furthermore,  that  Cicindela 
lecontei  and  the  green  tiger-beetle  {Cicindela  sexguttata)  belong  respec- 
tively to  different  and  older  situations  or  associations  ?  We  note  that  the 
habitats  in  which  the  species  occur  are  characterized  by  distinctly  differ- 
ent soils,  moisture,  amounts  of  shade  and  light.  We  note,  furthermore, 
that  these  animals  are  possessed  of  unusual  powers  of  flight  and 
are  able  to  select  conditions  suited  to  their  physiological  constitution. 
Their  mores  characters  are  definite  characters,  which  can  be  measured 
in  terms  of  reactions  to  measured  complexes  of  physical  and  other 
environmental  factors.  They  are  as  clearly  defined  as  any  morphological 
taxonomic  characters  and  can  be  measured  with  the  accuracy  of  any 
physical  phenomena. 

Doubtless  to  the  student  of  genetics  or  evolution,  the  question  of 
the  origin  of  such  characters  and  their  fixation  in  heredity  is  a  leading 
question.  At  this  point  we  know  little  or  nothing.  Since  nearly  all 
species  have  definite  habitat  preferences  and  since  many  varieties  differ 
slightly  from  the  related  species  form  in  the  matter  of  habitat  preference, 
it  is  probable  that  origin  of  a  slight  change  in  habitat  preference,  mean- 
ing a  slight  change  in  reaction  to  physical  factors,  a  change  in  ecological 
optimum,  is  usually  an  early  correlative  of  the  origin  of  new  races. 
Still  the  so-called  taxonomic  characters  may  remain  apparently 
unchanged,  while  marked  changes  in  habitat  preference  and  in  reaction 
to  physical  factors  are  being  brought  about  in  plastic  animals  (56). 
On  the  other  hand,  the  segregation  in  the  pure  lines  and  races  accom- 
plished in  experimental  breeding  often  appears  to  take  place  without 
any  regard  to  environment  (204).  These  two  facts,  accepted  as  they 
stand,  are  in  full  accord  and  we  might  conclude  that  there  are  no  rela- 
tions between  primary  ecological  characters  and  taxonomic  characters. 
Such,  however,  can  hardly  be  strictly  true,  but  we  cannot  see  what  the 
real  relations  may  be.  If  our  point  of  view  is  correct  the  ecological 
characters  of  a  race  experimentally  segregated,  or  experimentally  pro- 
duced, must  in  practice  consist  primarily  of  reaction  to  physical  factors 
or  combinations  of  physical  factors  or  to  entire  environmental  complexes; 
secondly  of  a  definite  rate  of  metabolism,  time  of  appearance  or  the  like; 


ECOLOGY  AND  BIOLOGY  317 

thirdly  of  specificity  of  behavior,  and  fourthly  of  structural  characters 
modifying  behavior.  Relatively  fixed  taxonomic  integumentary  charac- 
ters have  no  bearing  on  ecological  matters,  not  even  according  to  the 
broadest  definitions  of  the  subject.  The  characters  which  are  not  related 
to  the  environment  and  which  are  of  no  ecological  value  are  the  ones 
quite  generally  used  in  breeding  work,  specificity  of  behavior  standing 
second,  and  plastic  structure  third,  primary  ecological  matters  usually 
receiving  no  adequate  attention  or  only  suck  attention  as  comes  incidentally 
with  the  handling  of  the  material.  The  results  consist  of  noted  differences 
in  reaction  to  light  of  doubtful  intensity  and  quality,  or  similar  inaccu- 
rately measured  temperature  differences,  etc.  The  testing  of  primary 
ecological  characters  can  be  easily  conducted  and  will  answer  the  question 
before  us. 

^  With  all  of  its  imperfections  and  uncertainties,  the  ideas  of  phylogeny 
which  are  presented  in  our  phylogenetic  system  of  taxonomy  are  an  impor- 
tant asset  in  zoological  thinking  from  the  point  of  view  of  structure  and 
development.     The  classification  which  ecologists  are  striving  to  build 
up  will  serve  a  purpose  in  behavior,  physiology,  and  ecology,  analogous 
in  this  respect  to  that  served  by  the  phylogenetic  classification  in  morpho- 
logical thought,  but  should  be  flexible  rather  than  rigid  and  true  to  fact 
rather  than  to  schemes.     Figuratively  speaking,  an  ecological  classifica- 
tion cuts  taxonomy  vertically,  showing  many  structural  adaptations  as 
matters  of  stratum  or  over-adaptations  (205)  or  lack  of  adjustment  to 
conditions  (206,  206a).     It  also  cuts  it  again  horizontally,  showing  eco- 
logical similarity  in  organisms  structurally  and  phylogenetically  diverse. 
It  therefore  provides  a  new  and  different  means  of  organization  of  data. 
In  this  work  we  have  sharply  separated  evolution  and  structure, 
on  the  one  hand,  from  physiology  and  behavior,  on  the  other.     Space] 
clearness,  and  the  condition  of  the  subjects  have  forbidden  that  we' 
attempt  to  unite  them  here.     While  it  may  be  expedient  to  continue  in 
this  manner  until  our  knowledge  of  physiology  and  behavior  is  commen- 
surate with  that  of  the  other  subjects,  the  following  of  such  a  course 
indefinitely,  with  respect  to  either  morphological  or  physiological  aspects 
of  biology,  cannot,  if  it  be  general,  bring  about  the  best  development  or 
unification  of  biological  science.     Indeed,  its  present  lack  of  unity  is 
traceable  to  such  a  course  followed  until  recently  by  zoologists  generally. 
If  our  understanding  of  the  data  of  physiological  cytology  be  correct, 
we  may  expect  to  find  so-called  structures  of  some  sort  within  or  among 
the  cells  concerned  in  function,  which  stand  for  or  are  correlated  with 
each  physiological  state  and  physiological  condition  to  which  we  have 


3i8  ECOLOGY 

referred.  Our  methods  may  not,  at  present,  be  sufficiently  delicate  to 
detect  such  structure,  or  the  processes  which  lie  back  of  it,  but  we  may, 
it  is  believed,  confidently  expect  the  necessary  methods  for  the  detection 
of  such  structures  and  processes,  and  especially  their  correlation  with  and 
relation  to  the  more  permanent  and  more  easily  recognizable  morpho- 
logical conditions. 

We  classify  the  responses  and  changes  in  animals  as  evolution, 
modification  by  the  environment,  behavior,  and  physiological  response. 
Are  not  all  these,  after  all,  but  different  expressions  of  the  same  or 
similar  processes?  Future  investigations  must  answer  this  question, 
and  it  is  around  this  question  that  the  future  of  much  that  is  known  as 
biology  hinges. 

VII.     Relations  of  Ecology  to  Geography 

Ecology  is  primarily  the  study  of  the  mores  of  animals  and  animal 
communities.  It  is  fundamentally  a  branch  of  physiology — the  physi- 
ology of  the  relations  of  animals  to  their  environments.  While  we  may 
study  in  the  field  and  in  the  laboratory,  both  types  of  study  are  commonly 
conducted  with  reference  to  natural  environments.  Natural  environ- 
ments are  used  as  the  basis  for  study,  because  when  natural  environments 
are  destroyed,  animals  which  can  live  in  the  new  conditions  select  some 
one  of  several  possibilities  which  approach  the  normal  habitat.  Habits 
appear  particularly  variable  under  these  conditions.  Little  can  be 
gained  from  the  study  of  the  relations  of  animals  to  man-made  environ- 
ments, except  in  cases  where  the  species  has  long  been  living  under 
such  conditions  and  has  become  fully  adjusted  to  them. 

Ecology  being  a  subject  or  branch  of  physiology,  and  including 
all  of  the  sociological  side  of  animal  life,  its  relations  to  human  geography 
are  particularly  intimate.  Indeed,  geographers  have  been  disappointed 
with  the  data  which  zoology  has  furnished  them,  as  these  data  are 
almost  exclusively  data  concerning  the  taxonomy  and  morphology  of 
animals.  The  parallelism  between  the  geographic  phenomena  in  animals 
and  the  "relation  of  culture  to  environment"  lie  not  in  the  color  and 
structural  adaptations  of  animals,  but  in  the  behavior-characters  of 
animals  which  enable  them  to  live  under  a  given  set  of  conditions,  and 
the  behavior  which  those  conditions  produce  (207,  208,  209). 

While  attempting  to  make  comparisons  between  human  society 
and  man  on  the  one  hand,  and  plants  and  animals  on  the  other,  geog- 
raphers, sociologists,  and  psychologists — in  so  far  as  I  have  been  able 
to  read  their  writings  along  this  line — have  compared  structure  in  plants 


ECOLOGY  AND  GEOGRAPHY  319 

and  animals  with  what  is  obviously  not  structure  in  man,  namely,  his 
culture  and  mental  makeup.  Waxwieler  (210)  compares  human  society 
with  the  whole  animal  kingdom,  as  constituting  another  society.  McGee 
(211)  takes  a  similar  position.  In  discussing  the  relation  of  culture  to 
environment  he  says: 

When  the  law  of  biotic  development  is  extended  to  mankind,  it  appears 
to  fail;  for  the  men  of  the  desert  and  shore  land,  mountain  and  plain,  arctic 
and  tropic,  are  ceaselessly  occupied  in  strife  against  environmental  conditions 
which  transform  their  subhuman  associates;  yet  men  remain  essentially 
unchanged,  some  taller,  some  stouter,  some  swifter  of  foot,  some  longer  of  Hfe 
than  others,  yet  all  essentially  Homo  sapiens  in  every  characteristic. 

More  careful  examination  indicates  that  the  failure  of  the  law  when 
extended  to  man  is  apparent  only.  The  desert  nomads  retain  certain  common 
physical  characteristics,  but  develop  arts  of  obtaining  water  and  food  and  these 
arts  are  adjusted  to  the  local  environment 

He  continues  with  the  citation  of  other  cases.  Such  adjustment  of 
arts  (212)  is  comparable  to  the  adjustment  of  animals  with  regard  to 
food,  nest-building,  materials  used  in  nest-building,  and  other  features 
of  ecology  and  behavior.  Finally,  animal  ecology  offers  the  material 
and  methods  with  which  many  ideas  of  geography  may  be  experimentally 
verified  (213,  214). 


APPENDIX 

Methods  of  Study 
Methods  used  in  the  study  of  environment,  while  not  new,  involve 
the  methods  of  several  sciences.  To  determine  the  gross  features,  the 
methods  of  dynamic  and  historic  geology  and  physiography,  or  of  plant 
ecology,  must  be  applied.  For  further  analysis  the  methods  of  meteor- 
ology and  special  methods  for  measuring  the  environment  physically 
and  chemically  must  be  employed,  where  other  sciences  have  given  us  no 
data  and  method  (see  Clements).  These  consist  of  methods  of  studying 
the  rate  of  evaporation,  water  content  of  the  soil,  and  the  application 
of  meteorological  methods  to  climatic  details.  The  special  chemical 
methods,  aside  from  chemical  methods  of  the  study  of  the  soil,  consist 
of  detection  of  the  presence  of  excretory  products  in  the  soil  or  water. 
The  best  discussion  of  special  methods  is  given  in  the  references  (35a,  43, 
69.  74,  76,  77,  117,  118,  121,  124,  125,  129,  130,  131). 

METHODS   OF    STUDYING   ANIMALS   IN   THE   FIELD   AND   LABORATORY 

o)  Observation.—Ont  important  thing  in  ecological  study  is  simply  to 
sit  quietly  and  watch  animals,  and  record  what  they  do.  This  requires 
much  time,  and  the  best  observers  often  sit  for  hours  before  making  the 
desired  observations,  but  the  reward  is  always  adequate.  Some  good 
ecological  knowledge  has  thus  been  acquired.  One  difficulty  is  encoun- 
tered in  this  work.  When  the  observer  is  watching  one  animal  whose 
actions  are  not  of  especial  interest  at  that  moment  another  animal  often 
suddenly  appears  and  does  something  which  seems  of  importance  or 
which  is  of  especial  interest.  The  observer's  attention  is  diverted  from 
its  original  object  of  observation.  "Which  shall  I  continue  to  watch  ?" 
is  often  asked  by  the  student.  No  definite  rules  can  be  laid  down.  In 
general  it  is  probably  better  to  follow  the  original  object.  The  answer 
depends  entirely  upon  the  relative  ease  with  which  the  two  animals  before 
the  worker  can  be  observed.  The  beginner  cannot  answer  this  question 
and  only  experience  can  decide  which  should  be  followed. 

b)  Experimentation.— luvestiga.tion  in  ecology  requires,  in  prepara- 
tion, long  training  in  both  the  biological  and  physical  sciences.  Persons 
not  possessing  such  training  cannot  hope  to  make  important  contributions 
to  the  science.  Ecology  is  a  field  often  requiring  very  complicated 
experimental  methods.    Animal  behavior  and  some  aspects  of  physiology 

321 


322  ANIMAL  COMMUNITIES 

are  fundamental  in  ecology.  We  can  sketch  out  here  only  such  methods 
as  are  modifications  of  the  usual  method  of  these  branches  of  biological 
science  in  such  a  way  as  to  be  intelligible  to  those  somewhat  familiar 
with  such  laboratory  methods. 

(c)  Experiments  in  the  field  are  of  prime  importance  in  ecological 
work.  Here  smaller  animals  can  be  secured  in  numbers  and  subjected  to 
e.xperimental  conditions  before  their  physiological  state  has  been  modi- 
fied by  bad  treatment.  Any  student  competent  to  undertake  ecological 
investigation  will  find  no  difficulty  in  devising  apparatus  which  can 
be  carried  into  the  field  and  which  will  enable  him  to  do  work  of  a 
high  degree  of  scientific  accuracy.  Each  experiment  should  be  accom- 
panied by  a  control.  That  is,  the  same  number  of  animals  should  be 
put  under  the  same  conditions  as  in  the  experiment,  except  for  the  one 
factor  which  is  to  be  varied.  For  example,  in  an  experiment  designed 
to  determine  the  reaction  of  animals  to  light,  the  control  should  be 
either  equally  lighted  or  entirely  dark  (more  easily  accomplished),  and 
the  experiment  which  is  exactly  the  same  except  that  the  light  ranges 
from  darkness  to  bright  sunlight. 

The  apparatus  which  we  have  just  begun  to  develop  for  this  purpose 
is  still  in  need  of  much  perfecting.  Thus  far  it  consists  of  granite-iron 
and  galvanized-iron  containers  about  13  in.  long,  3  in.  deep,  and  4  in. 
wide.  These  are  provided  with  galvanized-iron  covers,  somew^hat  larger, 
and  a  little  deeper.  One  of  these  is  provided  at  one  end,  with  an  adjust- 
able slide  which  may  be  used  to  open  a  slit  to  admit  light  when  desired. 
In  connection  with  this  slit  a  mirror  is  provided  with  which  the  sunlight 
may  be  projected  into  the  pan  as  nearly  vertically  as  possible.  The  rays 
are  allowed  to  pass  through  a  water  screen  to  cut  out  the  heat.  For  work 
with  temperature  the  same  receptacles  have  been  used  and  temperature 
dififerences  secured  by  placing  one  end  of  the  experimental  tank  in  contact 
with  hot  soil  and  the  other  with  cold  soil.  Land  animals  are  confined  in 
tubes  II  in.  long  by  if  in.  in  diameter  with  round  bottom  and  close- 
fitting  cap,  shaped  like  the  bottom.  Reactions  to  gravitation  have  been 
tested  with  the  use  of  wire  cylinders  for  land  animals,  and  glass  cylinders 
lined  with  screen  for  aquatic  animals.  Black  covers  are  used  to  exclude 
light  in  various  ways  as  a  check.  For  the  study  of  reactions  to  current 
two  long  galvanized  boxes  (24X5X4  in.)  have  been  used,  one  having 
screen  ends  and  the  other  tight  ends.  They  are  placed  in  the  stream 
side  by  side,  one  serving  as  an  experiment,  the  other  as  a  control.  Large 
tin  pans  have  been  used  in  connection  with  the  long  boxes,  the  water  in 
the  experiment  being  stirred  so  as  to  produce  a  circular  current,  while  the 


METHODS  OF  STUDY  323 

control  is  left  undisturbed.  The  study  of  reactions  to  contact  has  been 
carried  on  by  the  use  of  pans  described  in  connection  with  light  and  tem- 
perature and  with  the  use  of  mica  chips,  leaves,  etc. 

In  all  experiments  the  containers  are  divided  into  several  divisions 
and  the  number  of  animals  noted  in  each  division  counted  at  each 
reading.  About  ten  readings  are  taken,  the  number  being  determined 
by  the  number  of  animals  used,  which  is  determined  by  the  number  that 
can  be  observed  before  they  can  move  any  considerable  distance.  This 
is  a  function  of  the  speed  of  movement,  which  also  determines  the  fre- 
quency of  reading.  Readings  should  be  taken  at  such  intervals  as  to 
enable  the  animals  to  completely  adjust  their  positions  with  reference 
to  the  conditions  in  the  interim. 

The  most  effective  method  of  study  is  that  of  mixing  animals  of  differ- 
ent habitats;  this  removes  the  necessity  of  accurate  measurement  for 
rough  comparison.  The  degree  of  accuracy  of  such  experiments  is 
determined  almost  entirely  by  the  ingenuity  and  care  exercised  by  the 
experimentor.  Accuracy  of  measurement  can  be  acquired,  but  in  the 
case  of  some  factors,  such  as  light,  with  some  difficulty.  Such  accuracy 
should,  however,  be  the  constant  aim  of  the  worker. 

While  a  high  degree  of  accuracy  may  be  attained  in  the  field  in  the 
case  of  some  factors  and  reactions,  it  is,  in  other  cases,  necessary  to 
perform  experiments  in  the  laboratory  also.  As  a  rule  all  experiments 
should  be  performed  in  both  field  and  laboratory. 

{b)  To  determine  the  most  important  activities :  The  first  step  in 
field  observation  is  the  continuous  watching  of  animals  throughout  a 
number  of  life  cycles.  Experimentation  is  almost  always  necessary  also. 
It  is  only  under  unusually  favorable  conditions  that  the  relative  impor- 
tance of  the  various  periods  of  the  life  history  of  an  animal  can  be 
ascertained  without  experimentation.  On  the  other  hand,  experimen- 
tation must  be  correlated  with  field  observation.  Simple  experimenta- 
tion on  the  behavior  of  animals  in  the  laboratory  does  not  illuminate 
this  matter  to  any  appreciable  extent. 

To  determine  the  habitat  preference  of  animals,  they  should  be  placed 
in  cages,  in  which  they  find  several  different  sets  of  natural  conditions, 
and  the  selection  made  by  the  animal  noted. 

METHODS  OF  TAKING  A  CENSUS 

Species  are  of  importance  because  each  usually  has  a  physiological 
makeup  and  habitat  preference  differing  from  other  species.  To  make  a 
census  of  the  animals  present  in  a  given  habitat  it  is  necessary  to  visit 


324  ANIMAL  COMMUNITIES 

the  place  at  various  times  of  day  and  night  and  at  various  times  of  the 
year,  to  overturn  and  open  all  loose  objects.  It  is  necessary  therefore  to 
collect  animals  which  have  been  observed  in  nature  in  such  a  manner 
that  the  correct  names  can  be  applied  later.  It  is  customary  to  assign 
numbers  to  the  animals.     The  method  commonly  used  is  as  follows : 

Loose  sheets  of  ruled  paper  are  filled  in  with  the  locality,  date, 
weather,  etc.,  carbon  copies  usually  being  made  as  a  matter  of  safety  and 
convenience.  Next,  an  animal,  say  a  spider,  is  observed  as  fully  as  time 
permits,  the  observations  are  recorded,  and  the  specimen,  if  small,  is 
placed  in  a  4-drachm  homeopathic  vial  containing  alcohol.  The  notes 
are  written  in  abbreviated  form  on  a  slip,  and  the  same  number  assigned 
to  the  notes  and  to  the  slip  which  is  put  in  the  bottle.  Animals  too  large 
to  put  into  bottles  are  prepared  in  the  same  way  by  tying  a  tag  to  them. 
In  due  time  the  bottle  is  sent  to  a  specialist  who  assigns  the  name,  which 
is  recorded  in  a  blank  space  on  the  note  sheet.  A  new  sheet  is  filled 
out  for  each  different  habitat,  and  later  all  the  sheets  relating  to  one 
kind  of  a  situation  can  be  brought  together. 

Nearly  all  animals  can  be  sufficiently  well  preserved  to  permit 
identification  by  specialists,  in  the  following  manner: 

a)  Vertebrates,  in  10  per  cent  formalin,  the  abdomen  opened  to  permit  the  fluid 

to  enter. 

b)  Crustaceans,  most  insects,  spiders,  worms,  and  lower  forms  by  dropping  into 

80  per  cent  alcohol. 

c)  Insect  larvae  and  pupae  must  be  subjected  to  high  temperature,  80°  C,  or 

they  will  turn  black.  Vials  or  bottles  containing  them  with  corks  removed 
should  be  set  in  a  pan  of  hot  water  for  20  minutes  immediately  after 
returning  from  the  field. 

d)  Flies  must  be  killed  by  poison  fumes,  pinned  in  the  field,  and  the  pins  set  in 

suitable  boxes. 

e)  Moths  and  butterflies  must  be  killed  by  fumes  and  pinned;  the  partial 

spreading  of  one  pair  of  wings  will  suffice  and  save  much  time. 


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Chapter  IV 

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1913- 

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204.  Cockerel,  T.  D.  A.    Aspects  of  Modern  Biology.     Popular  Science 
Monthly,  December,  pp.  540-48.     1908. 

205.  Coulter,  J.  M.    The  Theory  of  Natural  Selection  from  the  Standpoint 
of  Botany.    Fifty  Years  of  Darwinism,  56-71.     1908. 

206.  Wallace,  A.  R.     Malay  Archipeligo.    London.     1869. 

206a.  Hudson,  W.  H.    The  Naturalist  in  La  Plata.  '  (Ed.  of  1903,  Dent, 
London.)     1892. 

207.  Craig,   Wallace.    North  Dakota  Life;    Plant,   Animal  and  Human. 
Am.  Bull.  Geog.  Soc,  XL,  321-415.    Bibliography.     1908. 

208.    .     The  Voices  of  Pigeons  Regarded  as  a  Means  of  Social  Control. 

Am.  Jour.  Sociol.,  XIV,  86-100.     1908. 

209.  Tarde,  Gabriel.    Inter-Psychology.    Internat.  Quar.,  VII,  59-84.  1903. 

210.  Waxweiler,  E.     Equisse  d'une  sociologie.,   Inst.  Solvay  de  Soc.    Notes 
et  Mem.,  Fasc.  2,  306,  Bruxelles.     1906. 

211.  McGee,  W.  J.    The  Relation  of  Institution  to  Environment.     Smith- 
son.  Rep.,  1895,  pp.  701-11.     1896. 

212.  Mason,  O.  T.     Influence  of  Environment  upon  Human  Industries  or 
Arts.     Smithson.  Rep.,  1895,  pp.  639-65,     1896. 

213.  Tower,  W.  S.     Scientific  Geography;    the  Relation  of  Its  Content  to 
Its  Subdivisions.     Bull.  Am,  Geog.  Soc,  XLII,  801.     19 10. 

214.  Goode,  J.   Paul.    Human  Response   to   the  Physical  Environment. 
Jour,  Geog.,  pp.  333-43-     1894- 


INDEXES 


INDEX  OF  AUTHORS  AND  COLLABORATORS 

Page  numbers  followed  by  figures  in  parentheses  are  the  pages  of  the  Bibliography,  the  parenthetical 
figures  being  the  title  numbers;  the  numbers  following  the  parentheses  are  the  pages  on  which  the  articles 
are  cited  by  number.  Page  numbers  occurring  with  no  parenthesis  in  connection  are  those  on  which  the 
authors  and  collaborators  are  referred  to  independently  of  the  Bibliography. 


Abbot,  C.  C,  327  (53c),  34. 

Adams,  C.  C,  326  (35a),  22,  32,  42,  321; 

328  (67),  48;    329  (83),  73,  79,  19s; 

33^  (103J,  105,  no. 
Alden,  W.  C,  328  (60,  61),  44,  46,  47. 
Aldrich,  J.  M.,  viii. 
Allee,  W.  C,  vii,  viii,  91,  92,  188;  327 

(53).  33,  91;  327  (56),  35;  328  (73),  58. 
Atwood,  W.  W.,  45;  328  (62),  44,  46,  210. 
Audubon,  J.  J.,  v. 

Bachmetjew,  P.,  ^^s  (^33),  163. 
Baker,  F.  C,  vii,  viii;  330  (91),  83,  169, 

253,  256;  330  (100),  89,  102,  189,  193, 

265. 

Baker,  H.  B.,  335  (1800),  253. 

Banks,  N.,  vii,  viii;   334  (159),  195;    335 

(172),  222,  228,  240. 
Bates,  H.  W.,  v,  275. 
Beal,  F.  E.  L.,  325  (8),  9,  10. 
Beddard,  F.  E.,  336  (199). 
Belt,  T.,  v. 
Bernard,  Claude,  v. 
Betten,  C,  vii;  330  (95),  93. 

Beutenmiiller,  William,  265;    335  (188), 
258,  260. 

Birge,  E.  A.,  61;    328  (74),  59,  60,  125, 
321. 

Blanchard,  Rufus,  325  (15),  13. 

Blatchley,  W.  S.,  vii;  334  (156),  191,  198, 

244,  253,  25s,  258,  283. 
Bohn,  G.,  327  issa),  34,  305. 
Bollman,  C.  H.,  335  (183),  253. 
Brady,  G.  S.,  130. 
Braun,  M.,  326  (29),  20. 
Brehan,  Fabre,  — 
Brehm,  A.  E.,  v;  325  (2),  5. 
Briggs,  L.  J.,  331   (,117),   157,  321;    332 

("8),  157,321. 
Browning,  E.  B.,  3. 


Buffon,  V. 

Butler,  A.  W.,  331  (loJ 
i8r,  229. 


130,  132,  150, 


Caldwell.  O.  W.,  ix. 

Chamberlin,  T.  C,  328  (66),  47. 

Chaney,  R.,  viii. 

Child,  C.  M.,  vii,  ix,   108,   177-79;    326 

(37).  22,  23;   326  (370),  23. 
Chittenden,  F.  H.,  ix,  291,  293,  295. 
Clark,  F.  N.,  330  (90),  77. 
Class,  Elva,  viii. 
Clements,  F.  E.,  336  (197),  305. 
Cockerell,  T.  D.  A.,  336  (204). 
Cohnheim,  O.,  332  (126),  160. 
Colton,  H.  S.,  331  (114),  151. 
Comstock,  J.  H.,  233. 
Congdon,  E.  D.,  332  (123),  159. 
Cook,  O.  F.,  vii. 
Cope,  E.  D.,  327  (39),  24. 
Coulter,  J.  M.,  ix;  336  (205),  317. 
Cowles,  H.  C,  vi,  viii,  ix,  i,  174,  183,  286, 

310;    328  (58),  36,42;  332  (120;,  159, 

305;    336  (193),  305,  309. 
Craig,  W.,  336  (207,  208),  314. 
Cram,  W.  E.,  334  (162),  196. 
Cresson,  E.  T.,  viii. 
Cimningham,  Clara,  vii. 
Curtis,  W.  C,  330  (99),  99. 

Dachnowski,  A.,  331  (114(7),  151. 

Dahl,  F.,  V. 

Darwin,  Charles,  v,  24,  25;  326  (30),  20, 

159- 
DeCandolle,  161. 

Dickerson,  M.  C,  333  (139),  169,  195, 
234,  256,  283. 

Dimmit,  B.  H.,  vii,  278. 

Ditmars,  R.  L.,  334  (157),  252,  255. 


339 


340 


ANIMAL  COMMUNITIES 


Eigenmann,  C,  327  (41),  25. 
Ellsworth,  H.  L.,  326  (20),  14,  15. 
Emerton,  J.  H.,  Lx,  229,  238;   333  (138), 

169,  220,  222,  240,  252,  257,  258,  259, 

260,  261,  263. 

Fabre,  J.  H.,  v. 

Felt,  E.  P.,  333  (137).  166,  191,  195,  196, 
201,  225,  228,  229,  233,  257,  258,  259, 
260,  261,  266. 

Folsom,  J.  W.,  294;  334  (164),  214,  284. 

Forbes,S.  A.,ix,  283,  294;  325  (.5a),  9,17; 
325  (11),  10;  326  (26),  10,  17;  329 
(79)>  70,  76,  91,  92,  127.  140;  329  (85), 
75;  330  (89),  76,  77;  335  (174),  223, 
282,  284,  285;   335  (189),  267. 

Forel,  F.  A.,  v;  329  (76),  62-64,  321- 

Fowler,  H.  W.,  334  (i57»)>  i94- 

Fuller,  G.  D.,  332  (119),  158;  332  (119a), 
158;  332  (131).  162,  249,  250;  332 
(131a,  1316). 

Ganong,  W.  F.,  327  (52),  33. 

Gerhard,  W.  J.,  vii,  ix,  196. 

Giard,  A.,  v. 

Gill,  T.,  331  (106),  126,  149- 

Gleason,  H.  A.,  329  (83,  2),  79,  83;   335 

(176),  229. 
Goldthwait,  J.  W.,  4S;   328  (62,  63,  64), 

44,  46. 
Goode,  J.  P.,  ix;  336  (214),  319. 
Gorham,  F.  P.,  ix,  60. 
Graves,  H.  S.,  332  (124),  159,  321. 
Greeley,  A.  W.,  333  (132),  163. 

Haase,  E.,  v. 

Haddon,A.  C.,325(4),8. 

Hancock,  J.  L.,  vii;  327  (40),  25,  34,  181, 

190,  195.  198,  215,  218,  223,  226,  227, 

232,  235,  241,  252,  255,  259,  260,  262, 

266,  268,  270. 
Hankinson,  T.  L.,  331  (105),  125,  126, 

140,  151. 
Hann,  J.,  332  (125),  160,  161,  162,  163, 

321. 
Hart,  C.  A.,  vii;  335  (176),  229. 
Harvey,  N.  A.,  vii. 
Haswell,  W.  A.,  326  (36),  22. 
Heilprin,  A.,  336  (192),  299. 
Heinemann,  P.  G.,  viii. 
Henshaw,  S.,  viii. 


Herms,  W.  B.,  334  (169),  219,  223. 
Herrick,  C.  L.,  ix. 
Herrick,  F.  H.,  327  (49),  32,  34. 
Hildebrand,  S.  F.,  vii,  130;  329  (84),  73, 

78,  84. 
Hine,  J.  S.,  329  (83,  8);  333  (140),  170. 
Holmes,  S.  J.,  327   (536),  34,  3°5;    333 

(148),  177. 
Holt,  W.  P.,  329  (83,  4). 
Hopkins,   A.   D.,   334    (160),    195;    334 

(161),  195,  196. 
Horn,  W.,  336  (203),  315. 
Hortag,  M.,  326  (28),  20. 
Hoskins,  W.,  viii. 

Howard,  L.  O.,  221;  335  (i79)>  256,  267. 
Hoy,  P.  R.,  329  (82a),  80. 
Huber,  P.,  v. 

Hudson,  W.  H.,  iv;  336  (206a),  317. 
Huntingdon,  E.,  332  (127),  160. 

Indian    Affairs,    Commissioner    of,    325 

(16),  13. 
Isely,  F.  B.,  188;  330  (990). 

Janet,  C,  v. 

Jennings,  H.  S.,  ix;  327  (44),  27,  34,  77, 

299,  300;  330  (87,  88),  75,  76,  77. 
Joh'annsen,  O.  A.,  330  (98),  144. 
Johnstone,  J.,  327  (47),  31,  35,  58,  66,  68. 
Jones,  A.,  326  (23),  14. 
Jones,  F.  M.,  334  (158),  193. 
Juday,  C,  vii,  133;  328  (74),  59,  60,  125; 

331  (104),  125;  331  (no,  III),  133. 
Judd,  Sylvester  D.,  336  (191),  274. 

Kellogg,  V.  L.,  ix,  225,  270,  272. 
Kennicott,  R.,  326  (22),  14,  15,  171,  196, 

241,  289. 
Kent,  W.  S.,  75. 

Kingsley,  J.  S.,  326  (33),  21;  330  (ggb). 
Kirkaldy,  G.  \V.,  335  (186),  257. 
Kirkland,  A.  H.,  325  (10),  9. 
Kirkland,  J.,  325  (14),  13. 
Kofoid,  C.  A.,  329   (75,  app.),  74;    329 

(77),  67,  103,  125,  321. 
Kuntz,  G.  F.,  326  (31),  21. 
Kwiat,  A.,  vii. 

Lamarck,  J.  B.,  24,  25. 
Lane,  A.  C.,  45;  328  (65),  44. 


INDEX  OF  AUTHORS 


341 


Lefevre,  G.,  330  (99),  99. 

Leidy,  J.,  75,  130. 

Leverett,  F.,  45;  328  (59),  44. 

Lillie,  F.  R.,  ix. 

Livingston,  B.  E.,  332  (130,  130a,  130^, 

130c),  162. 
Loeb,  J.,  vi;  328  (72),  58,  305. 
Lugger,  O.,  88,  234;  S33  (^5°),  180,  191, 

273;    334   (155),   192,   201,    233;    334 

(163),  199,  202,  215. 

Lydekker,  A.,  336  (200). 
Lyon,  E.  P.,  323  (94),  91,  lor. 

MacGillivray,  A.  D.,  vii;   331  (109),  132. 
Marlatt,    C.  L.,   ix,  220,  265,  282;  335 

(178),  252. 
Marsh,   C.   D.,   vii;    329   (78),  67;    33^ 

(146,  146a),  176. 
Marsh,  M.  C,  326  (24),  17;  328  (71),  58, 

59- 
Mason,  E.  G.,  326  (19),  14. 
Mason,  O.  T.,  336  (212),  319. 
Mast,  S.  O.,  327  (45),  28,  159. 
McFarland,  Joseph,  326  (27a). 
McGee,  W.  J.,  336  (211),  319. 
McLane,  J.  W.,  331  (117),  157. 
McNutt,  W.,  332  (119a),  158. 
Meek,  S.  E.,  vii,  ix;   329  (84)  73,  78,  84. 
Merriam,  C.  H.,  327  (48),  32,  299;    333 

(142),  171,  189,  195,  196,  233,  238. 
Meyers,  I.  B.,  220. 
Milner,  J.  W.,  329  (81),  73,  80,  83,  84. 
Mobius,  K.,  V. 
Moore,  B.,  327  (43),  26,  321. 
Moore,  J.  P.,  vii;   330  (91a),  83. 
Morse,  A.  P.,  329  (83,  6). 

Needham,  J.  G.,  329  (83,  7);  330  (95), 
93.  96,  146;  33°  (96),  95;  330  (98),  99; 
334  (168),  219. 

Newman,  H.  H.,  331  (107),  130. 

Nichols,  Susan  P.,  viii. 

Nichols,  W.  R.,  326  (25),  17. 

Ortmann,  A.  E.,  \di;   330  (loi),  104. 
Osborn,  H.  F.,  327  (38),  24. 
Osburn,  R.  C,  vii. 
Osgood,  W.  H.,  viii. 

Packard,  A.  S.,  334  (154),  191. 
Park,  W.  H.,  326  (27),  20. 


Parker,  T.  J.,  326  (36),  22. 

Parkman,  F.,  326  (18),  14. 

Pearl,  R.,  333  (144),  172. 

Pearse,  A.  S.,  330  (loio). 

Peckham,  G.  W.  and  E.  G.,  223;    335 

(173),  222,  252,  255,  258;    335  (187), 

258. 

Peet,  M.  M.,  329  (83,  12). 
Pettenkoffer,  M.,  162. 

Reed,  C.  A.,  334  (153),  181,  189. 
Reed,  H.  S.,  332  (121),  159. 
Reeves,  C.  D.,  330  (97),  95. 
Reighard,  J.,  327  (50),  32,  90,  91,  loi. 
Reynolds,  John,  326  (20a),  14,  15. 
Richardson,  H.,  335  (182),  253. 
Richardson,  R.  E.,  329  (79),  70,  91,  92, 

99,  127,.  140. 
Riddle,  O.,  327  (46),  31. 
Riley,  C.  V.,  ix,  201,  234,  238. 
Ritter,  W.  E.,  325(i),5. 
Robertson,  C.,  335  (181),  253,  255. 
Romanes,  G.  J.,  v. 
Roosevelt,  T.,  35;  325  (3),  5,  313. 
Ruthven,  A.  G.,  325  (7),  9;  329  (83,  11); 

334  (152),  viii,  181;  335  (180). 

Salisbury,  R.  D.,  ix;  328  (57),  36,  44,  61, 

73,  157;   328  (60),  44. 
.Schimper,  A.  F.  W.,  328  (58a),  36,  38,  313, 

314- 
Schmarda,  L.  R.,  v. 
Schreiner,  O.,  332  (121),  159. 
Scudder,  S.  H.,  335  (171),  222, 
Selous,  F.  C.,  336  (201). 
Semper,  K.,  327  (51),  i,  33. 
Seton,  E.  T.,  333  (143),  171,  195,  269. 
Severin,  S.,  10. 

Shantz,  H.  L.,  332  (118),  157,  321. 
Sharp,  D.,  326  (34),  21. 
Sharpe,  R.  W.,  vii,  144;   333  (147),  177. 
Shelford,  Mabel  Brown,  vii,  13-15. 
Shelford,  V.  E.,  325  (6),  9,  32,  59,  68,  69, 

136,  151,  152;  325  (13),  12,  33,   311; 

327  ^55),  34,  36,  37,  38,  157,  161,  209, 

211,  215,  301,  302,  304,  315;  328  (73), 

58;  330  (92),  90,  99.  105,  309;  331 
(112),  136,  152;  331  (115),  157,  222. 
225,  227,  233;  333  (134),  163;  333 
(151),  211,  215,  219,  252,  256;  334 
(1510),  229;  335  (170),  219,  225,  227, 
233- 


342 


ANIMAL  COMMUNITIES 


Sherff,  E.  E.,  333  (136),  165. 

Sherman,  J.  D.,  330  (99c),  99,  102,  104, 

105,  180,  193. 
Shimek,  B.,  335  (135),  164. 
ShuU,  C.  H.,  335  (175),  227,  257. 
Smith,  B.  G.,  330  (93),  91. 
Smith,  Fiank,  vii. 
Smith,  H.  M.,  ix,  79. 
Smith,  J.  B.,  176,  179;    333  (145),  174; 

335  (177),  252,  253,  259,  260,  261. 
Smith,  S.  I.,  ix;   329  (80),  73,  76,  78. 
Snow,  Julia  W.,  330  (86),  75. 
Snow,  Laetitia  M.,  334  (167),  219. 
Sparks,  J.,  32s  (17),  13. 
Stahl,  W.  S.,  viii. 
Stanfuss,  M.,  327  (42),  25. 
Stephens,  T.  C,  viii,  170,  171,  175,  228, 

229. 
Stevenson,  C.  H.,  326  (32),  21. 
Stimpson,  W.,  329  (82),  73,  78,  80,  84. 
Stone,  W.,  334  (162),  196,  227. 
Strong,  R.  M.,  viii. 
Surface,  H.  A.,  325  (9,  90),  9;  334  (166), 

219. 

Tarde,  G.,  336  (209),  318. 
Thompson,  C.,  334  (152),  181. 
Thompson,  H.,  334  (152),  181. 
Thomson,  J.  A.,  6. 
Titcomb,  J.  W.,  331  (113),  140,  142. 
Titus,  E.  S.,  329  (83,  9). 
Tower,  W.  S.,  336  (213),  319. 
Transeau,  E.  N.,  50,  51,  64;    328  (69), 

164,  321;  328  (70);  332  (122),  159. 
Turner,  C.  H.,  ix. 

Van  Hise,  C.  R.,  331  (116),  157. 
Verworn,    Max,    326    (35),    22,    27,    28, 
300. 


Visher,  S.  S.,  vii,  viii,  190. 
Voit,  C,  162. 

Wagner,  George,  331  (no),  133. 
Walker,  A.  C.,  332  (128),  160,  299. 
Walker,  Bryant,  329   (83,   5),   83;    329 

(75,  app.),  80,  83-85. 
Wallace,  A.  R.,  v;   336  (206),  317. 
Ward,  H.  B.,  329  (75),  62,  64,  67,  73, 

74,  82,  83-85. 
Ward,  T.,  336  (202). 
Warming,  E.,  325  (12),  12. 
Washburn,  F.  L.,  ix,  225,  239,  290,  291; 

335  (190),  272,  285. 
Waxweiler,  E.,  336  (210),  319. 
Weather  Bureau,  328  (68),  49. 
Webb,  Sidney,  325  (5),  8. 
Weckel,  A.  L.,  vii;  331  (102),  104. 
Weed,  C.  M.,  335  (184),  253. 
Wells,  M.  M.,  vii,  ix. 
Wheeler,  W.  M.,  327  (54),  34,  252,  253, 

255;  329  (83,  lo)- 
White,  G.,  V. 

Whitford,  H.  N.,  336  (198),  311. 
Wickham,  H.  F.,  vii. 
Wiesner,  J.,  160. 
WiUiston,  S.  W.,  89,  217,  224,  271,  272; 

334  (165),  214,  217,  222. 
Wirtner,  P.  M.,  335  (185),  257,  259. 
Wokott,  A.  B.,  vii,  196;  329  (83,  3),  193. 
Wolcott,  R.  H.,  vii,  130;  333  (149),  177. 
Wood,  F.  E.,  326  (21),  viii,  14,  15,  34, 

192,  196,  255. 
Wood-Jones,  F.,  336  (195),  305,  309. 
Woodruff,  F.  M.,  333  (141),  171,  181. 
Woodruff,  L.  L.,  336  (196),  305,  309. 

Yapp,  R.  H.,  332  (129),  160,  165. 

Zon,  R.,  332  (124),  159,  321. 


INDEX  OF  SUBJECTS 


Absorption  of  dissolved  foods  by  aquatic 
animals,  58. 

Acclimatization,  isopods,  92. 

Acorns:  eaten  by  squirrels,  233;  weevils, 
233- 

Activities:  classification  of,  31;  dis- 
tribution and,  299-305;  environment 
and,  26-30;  form  and,  26-27;  rnost 
limited,  304. 

Adaptation:   24-26;  of  May-fly  nymphs, 

96. 
African  game,  7. 

Age  of  habitats:  44;  forest,  218,  247; 
lakes,  133-34;  ponds,  138,  152; 
quantity  of  life  and,  68-69;  streams, 
86,  1 10-14. 

Agriculture:   communities  of,  13 ;  15-17; 

near  cities,  19. 
Algae:    59,  65,  70;    depth  limit  in  Lake 

Michigan,  74;    filamentous,  131,  148; 

on  mollusk  shells,  126. 

Ammonia:  in  sewage,  17;  in  air  and 
water,  59,  60;  in  nitrogen  balance,  66; 
reactions  of  fishes  to,  60. 

Amphibians  or  Amphibia,  scientific 
names: 

—Acris  gryllus,  135,  169,  296. 

— Amblystoma  tigrinum,    149,   278,    282, 

296. 
• — Bufo  lentiginosus,  187,  296. 
— Chorophiliis  nigritus,  195,  206,  283,  296. 
— Dicmictyhis  viridcsceiis,  121,  149,  156. 
— ■Hemidactylium  scutaiuni,  237. 
— Hyla: 

pickeringii,  194,  195,  196,  205,  207, 

234,.  253. 

versicolor,  205,  234. 
— Neciurus  maculosus,  130. 
— Plethodon: 

cinereiis,  197,  207,  243,  244,  256. 

glutinosus,  181,  183,  207. 
— Rana: 

catesbeiana,  171. 

clamata,  169,  171,  195. 

pipiens,  156,  169,  195,  296. 

sylvatica,  195,  206,  207,  243,  244,  256. 
Amphipods,  69,  70. 

Amphipods  or  Amphipoda,  scientific 
names : 


— Eucraiigo)iyx,  174: 

gracilis,  80,  85,   114,  118,   150,   154, 
185,  206. 
— Gavmiarus  fasciatus,  90,  93,  104,  114, 

118,  123,  172. 
— Hyalella  knickcrbockeri,   78,   104,   114, 

121,  123,  135,  144,  154. 
— Pontoporcia  hoyi,  80,  81,  85. 

Anemotaxis,  161. 

Animal  organism,  22-33. 

Animals:  disappearance  of,  near  Chicago, 
13-15;  economic  value  of,  20;  rela- 
tion of,  to  man,  5-20. 

Annelida,  103.    See  also  Leeches. 

— Lumbriciihis,  179: 
inconslans,  185. 
• — ■Limnodrilus  claparedianus,  83. 

Ant-Uon,  229,  232. 

Ants:  167;  aphids  and,  234,  255,  290; 
swarming  of,  227. 

Ants,  scientific  names: 
— A  phaenogaster: 

tennesseensis,  256. 

ireatae,  188. 
— Campoiiotiis,  202: 

herciileanus    lignipcrdiis     novebora- 

censis,  207,  255. 

herciileanus  pennsylvanicus,  253. 
— Dolichoderus  mariae,  204. 
— Formica: 

cinerea  neocinerea,  298. 

fusca,  204,  205,  207. 

fusca  siibsericea,  187. 

subpolila  neogagates,  282,  297. 
• — Lasiiis: 

niger  amcricanus,  227,  252. 

nmbratus  mixtus  aphidicola,  234,  255. 
• — Myrmica  rubra  scabrinodis,  288,  297. 
— Ponera  coarctata,  187. 
Aphids:     167,  245;    ants  and,  234,  290; 
cherry,  223-24;  consocies,  37,  214,  290; 
fecundity  of,  18,  35;  grain,  18;  housed 
by  ants,  234. 
Aphis-lions,  167,  290-91. 
Aquatic    conditions:     58-67;     chemical, 
58-60;    food,  65-67;    physical,  60-65. 
Ash:   190;  gaUs  of  midrib,  192. 
Association:  37;  defined,  38;  Usted,  39- 
41. 


343 


344 


ANIMAL  COMMUNITIES 


Atmometer,  162,  164. 

Atmosphere:      159;      composition,     59; 

evaporating    power,    159-62,    248-50; 

currents  in,  161. 

Back-swimmers,  65,90,  117,  123, 132, 135, 

148,  151,  155. 
Bacteria:    denitrification,  66;    nitrifying, 

66;    nitrogen-fixing,  66;    number  and 

age  of  ponds,  68;  number  and  quantity 

of  life,  66;  soil,  159. 
Bacteria,  scientific  names: 
— Azotobacler,  66. 
— Backrium  actinopelte,  66. 
— Clostridium,  66. 
— Nitrobadcr,  66. 
— Nilrococcus,  66. 
— Nitrosomonas,  66. 
Badger,  15,  167,  288. 
Balance  in  nature:   17-18;   restored  after 

the  rise  of  a  pest,  18;  after  disturbance 

in  water,  71. 
Bark  beetle:    destroyer,   195;    habits  on 

tamarack,  195;   on  pine,  228. 
Bass,  black:    22,  23;   large-mouthed,  70, 

71,  85,  115,  120,  126,   127,   141,   156; 

rock,  85,  99,  119;    small-mouthed,  85, 

99,    119,    120;     warmouth,    130,    142, 

156. 
Bear,  black,  14,  15,  201,  237,  245. 
Beaver,  15,  loi,  199. 
Beech  woods,  158,  242-52. 
Beetles,  aquatic:    brook,  78,  93,  96,  98, 

loi,  102,   104,   118,   121,   123;    preda- 

ceous  diving,  65,  90,  102,  104,  121,  131, 

'^3S,   151;    water  scavenger,   65,   104, 

131,  151,  185. 

Beetles,  aquatic,  scientific  names: 
— Agahiis,  9c: 

semipunctatus,  151. 
■ — Aphodius  fiinetarius,  185. 
— Chrysomelidae,  132. 
■- — Coptotomus  interrogatus,  135. 
— Cybister  fimbriolatus,  149. 
— Dascyllidae,  179,  185. 
— Donacia,  65,  123,  135,  151. 
— Dytiscidae,  65,  102,  104,  131,  151,  185. 
— Elmis,  121: 

fastiditus,  93,  118. 

4-notatus,  123. 

quadrinotatiis,  104. 
— Haliplidae,  65. 

— Hydro philidae,  65,  104,  131,  151,  185. 
■ — Hydro porus,  90: 

mellilus,  102. 

viUatus,  121. 
— Parnidae,  78,  96,  98,  loi,  102. 


— Psepheniis,  78,  96. 

Beetle:  bark,  195,  228;  boring,  191,  206, 
217,  240;  click,  234,  25s,  282,  297; 
ground,  167,  179,  180,  185,  186,  190, 
217,  205,  206,  272,  243;  lady,  167, 
293;  May,  167,  290;  relation  to  moist- 
ure, 247;  snout,  223,  238,  282,  284; 
soldier,  167. 

Beetles,  terrestrial,  scientific  names: 
— Acmaeodcra  pidcheUa,  297. 
— Acrapteryx  gracilis,  277. 
— Alans: 

myops,  255. 

ocidalus,  253. 
— AUopoda  lulea,  207. 
— A  mora: 

aligns  lata,  296. 

polita,  204. 
— Anisdactylns  i titer punctaliis,  218. 
— Anthophilax  atknuatus,  245. 
— Baris  confinis,  204. 
— Bassareits  lativittis,  258. 
— Bembidium,  185,  198: 

carinula,  179,  180,  186. 

variegalHin,  186. 
— Boletobiiis  ductus,  261. 
— Boletothcrus  bifurcus,  244,  261. 
— Brachybamus  electus,  204. 
— Buprestidae,  191,  201. 
— Calathus  gregarius,  217. 
— Callida  punctata,  276,  277. 
— Calligrapha,  267: 

multipunclata,  188,  207. 

scalaris,  241,  260. 
— Cardiophorus  cardisce,  255. 
— Cerambycidae,  191,  206,  217,  240. 
— Ceruchus  piceus,  253. 
— Chalepus: 

hornii,  188. 

nervosa,  207. 

scapularis,  208. 
— Chelymorpha  argus,  277. 
— Chlaenius  aestivus,  296. 
— Chrysochus  auratus,  284,  297. 
— Cicindela: 

cuprascens,  180,  186,  219. 
formosa  generosa,  225,  226,  252. 

hirticollis,  179,   180,   186,   219,   221, 

315- 

lepida,  40,  120,  223,  252,  316. 
purpurea  limbalis,  40,  210,  211,  212, 
213,  254,  302. 
repanda,  181,  186. 
saulcyi,  315. 

scutellaris  Iccontei,  40,  182,  227,  229, 
230,  252,  316. 

sexguttata,  41,    215,    216,    234,    254, 
256,  316. 

tranquebarica,  182. 
— Cleridae,  194. 


INDEX  OF  SUBJECTS 


345 


Beetles — Conlinucd: 
— CocciucUdae,  224. 
— Coptocyda: 

bicolor,  205,  277. 

clavala,  206. 

sign  if  era,  277. 
— Crepidodcra  helcximis,  108. 
— Cryptoccplialiis: 

ciiictipcnuis,  297. 

vcnuslus,  284,  297. 
— Cryptorhopahim  hacmorrhoidalc,  207. 
— CryptorhyncliHs  lapathi,  267,  276. 
— Cycloneda,  293: 

sail  guinea  vninda,  298. 
— Cyp/ion: 

padi,  207. 

variabilis,  207. 
— Dascyllidac,  207. 
— Dcctes  spinosus,  277. 
— Dendroctoniis  simplex,  195. 
— Dcrmesles  lardariits,  16. 
— Dermestidae,  207,  217,  219. 
— Desmoris  scapalis,  297. 
— Diabrotica: 

i2-piinelala,  187,  284,  297. 

viltata,  187. 
— Diaperis  Iiydni,  234,  253. 
— Diplochila  laticollis,  296. 
— Disonycha  quinqnevittala,  224,  258. 
— Ditonia  qiiadri guttata,  259. 
— Donacia  subtilis,  297. 
— Doryphora  clivicoUis,  270,  277. 
— Eburia  quadrigeminata,  119. 
— Elaphidion  villosum,  239,  241,  277. 
— Elateridae,  234,  255. 
— Endalus  limaiulus,  284,  297. 
— Epicuata,  270: 

marginata,  277. 

peinisyliHuiica,  277. 
— Eupsa/is  minida,  201,  255. 
— Eustrophus  tormentosus,  234. 
— Galcrita  janiis,  253. 
— Geopinus  inerassatus,  220. 
— Geotrupes  spleudidus,  256. 
— Haltica  igiiita,  192. 
— Helophorus  lineatus,  204. 
— Hippodamia,  293: 
parenthesis,  292. 
— //'5  grandicoUis,  228,  258. 
— Laeon  reclangularis,  255. 
— Lampyridae,  205. 
— Languria: 

angustata  trifasciata,  277,  255. 
gracilis,  205. 
mozardi,  293,  294. 
— Lebia  atriventris,  277. 
— Limonius  interstitialis,  208. 
— Zmo,  267: 

scripta,  276. 
■ — Listotrophus  cingulatus,  207. 


— Listronotus: 
callosus,  204. 

inaequalipennis,  204. 
— Lixus,  293: 

macer,  277. 

concavus,  295. 
— Lucidota: 

atra,  188. 

pioictala,  188. 
— Mcgalodacnc  lieros,  247. 
— Mcgilla,  293: 

maculata,  292,  293. 
— Mclandryidae,  206,  207. 
— Melanolus: 

communis,  256. 

Jissilis,  282,  297. 
— Meracanlha  contracta,  253. 
— Monachus  saponatus,  284,  297. 
— Mordelliste  na: 

aspcrsa,  188. 

connata,  298. 
— Nitidulidae,  267. 
— Nodonola  tristis,  188,  258,  297. 
— Obcrca  tri punctata,  277. 
— Odontota  nervosa,  260,  297. 
• — Orthosoma  brunncum,  239,  253. 
— Pachybrachys,  293,  298: 

abdominalis,  188. 
— Pachyscelus  laevigatus,  188. 
— Parandra  brunnea,  190. 
— Passalus  cornutus,  239,  240,  242,  247. 
— Pelidnola  punctata,  208,  277. 
— Pentlte  pimelia,  247. 
— Phloeotrya  quadrimaculata,  207. 
— Photinus: 

corruscus,  207. 

punclulatus,  298. 
— Pissodes  sir  obi,  196. 
■ — Platynus.  192: 

ajfinis,  296. 

deccns,  205. 

picipennis,  204. 
— Plectrodera  scalator,  225,  258. 
— Podabrus: 

basilaris,  261. 

rugulosus,  208. 
— Polygraphus  rufipennis,  194,  195,  206. 
— Prionus,  233,  239. 
— Psyltobora  20-macidata,  207. 
• — Pterocyclon  mali,  246. 
— Ptcrostichus: 

adoxus,  206,  207,  243. 

coracinus,  206. 

lucublandus,  205. 

pennsylvanicus,  206. 

5a>"',  255. 
— Ptilinus  ruficornis,  245. 
— Ptilodactyla  serricollis,  188. 
— Pyraclomena  boreaiis,  188. 
— Pyrocliroidae,  191,  201,  247. 


346 


ANIMAL  COMMUNITIES 


Beetles — Continued: 
—Rhinoncus  pyrrhopus,  208. 
— Saperda: 

concolor,  267,  276. 

lateralis,  276. 
— Saprimis  patriiclis,  186,  219. 
— Scarabaeidae,  207,  286. 
— Silpha  surinamensis,  253. 
— Sphcnopliorus,  223: 

pcrlinax,  284. 
— Staphylimis  violacais,  256. 
— Stereopalpiis: 

hadiipCHiiis,  219. 

mcllyi,  188. 
— Strangalia  acuminata,  208. 
— Synchroa  punctata,  206. 
— Tachinus  pallipes,  260. 
— Telephorus  lineola,  204. 
— Tencbrionidae,  201,  217. 
— Tetraopes  tctraophthalmus,  270,  297. 
■ — Thanasimus  dubius,  194,  195,  206. 
— Tharops  ruficornis,  247. 
— Tomicus.     See  Ips. 
— Trirhabda  tormentosa  canadensis,   276, 

293,  297. 
— Tritoma  unicolor,  244. 
■ — Typophorus: 

canellus,  282,  284. 

canellus  aterrimus,  188,  297. 

canellus  gilvipes,  298. 

canellus  sellatus,  188. 
— Uloma  jmpressa,  255. 
— Xanthonia  lo-notata,  241,  260. 
— Xylopinus  saperdioides,  256. 

Behavior  rhythms,  related  to  tide,  34. 

Bionomics,  32. 

Biota,  defined,  34. 

Birds:  economic  value  of,  8-1 1;  protec- 
tion of,  8-1 1,  57;  feeding  grounds  of 
aquatic,  130,  132. 

Birds,  scientific  names: 

• — Ar  delta  ex  His,  171. 

— Empidonax  trailli,  190. 

— GaUinula  galeata,  171. 

— Tyrannus  tyrannus,  228. 

— Xanthocephalus  xanthocephalus,  170. 

Bison,  14,  201,  283,  289. 

Bittern:   American,  171;   least,  171. 

Blackbird,  red-wing,  171,  174,  175; 
yellow-head,  170,  171. 

Black  fly,  87-89,  93,  95,  105,  114,  116, 
118. 

Blowouts,  229. 

Blue  racer,  227. 

Bluebird,  242. 

Bluejay,  242,  244. 


Bobolink,  9,  167,  283,  289. 

Bobwhite,  269,  275. 

Borers:  buprestid,  191;  cerambycid, 
191;  of  trees,  191;  four  marked,  191; 
common  to  swamp  forest  trees,  191. 

Bottom:  communities  of,  in  Lake 
Michigan,  77-80;  distribution  on, 
107,  108;  factor,  43;  gravel,  91; 
important,  64;  in  deep  water,  80;  lake, 
125;  pond,  140,  141;  stony,  95; 
stream,  86. 

Braconids,  290. 

Breeding:  of  aquatic  insects,  65;  of  birds 
{see  common  names  of) ;  of  brook 
fishes,  90-91;  of  lake  fishes,  126;  of 
mammals  {sec  common  names  of) ;  of 
mites,  129;  of  musk  turtle,  130;  of 
jx)nd  fishes,   141. 

Bronzed  grackle,  275. 

Brook  trout,  31. 

Brook-mores  of  sowbug,  90. 

Brown  thrasher,  268,  275. 

Buffalo  iish,  130. 

Bullhead:  70;  speckled,  126,  141,  156; 
black,  102,  119,  120,  149,  156;  yellow, 
156. 

Bumblebee,  190. 

Bunting:  indigo,  268,  274,  275;  lark,  289. 

Buttonbush,  190. 

Cabbage  butterfly,  221,  222,  227. 

Caddis-flies,  65. 

Caddis- worms:  caseless,  88,  116;  case- 
weighting,  125,  126,  135,  140,  143, 
15s;  leaf-tube  making,  39,  105,  114, 
121,  146,  148,  155,  174,  185;  mores  of, 
126;  sand-tube  making,  39,  142,  143, 
148,  155;  sandy  bottom,  135;  spiral- 
cased,   96,   99,    117,   121;   stick-using, 

lOI. 

Caddis-worms,  scientific  names: 

— Chimarrha  sp.,  116. 

—Goera,  125,  135,  140,  142,  143,  155. 

— Helico psyche,  96,  99,  117,  121. 

—Hydropsyche,  39,   79,  93,   94,   95,   96, 

105,  107,  118,  121,  123. 
— Lcptoceridae,  143,  148,  39,  155,  442. 
— Limnophilidae,  117. 
— Molanna,  125,  134. 
— Neuronia,  39,  148,  155,  185. 
— Phryganeidae,  105,  114,  121,  146,  148, 

174. 
— Polyccnlropidae,  135. 
• — Rhyacophila,  88. 
— RhyacophiUdae,  88. 


INDEX  OF  SUBJECTS 


347 


Calumet  beach,  46. 

Carbon  dioxide:  important  to  animals, 
59,  60;  in  air,  59;  in  ponds,  68;  in 
sewage,  17;  in  springs,  93;  in  streams, 
86;   relation  to  quantity,  66-70. 

Carp,  31,  120,  130. 

Carrion:   219;   feeder,  219. 

Catbird,  268,  275. 

Caterpillar:  achcmon  sphinx,  232; 
American  dagger-moth,  192;  cecropia, 
198,  199;  common  to  marsh  forest 
trees,  192;  forest  tent,  192;  hickory 
tussock-moth,  192;  maia  moth,  26S; 
prominent,  232,  233;  puss,  232;  slug, 
233;  smeared  dagger-moth,  192;  vice- 
roy, 198,  199;  white-marked  tussock- 
moth,  192. 

Catfish,  lake,  85.     Sec  Bullhead. 

Cecidomyiidae,  215,  229. 

Center  of  distribution,  303. 

Cliara,  bottoms  covered  with,  140,  141, 

142.   145;    communities,   140-45;    not 

good  animal  food,  142. 

Characters  of  communities  of  forest,  250, 
251. 

Chicago  region:  climate,  former,  47, 
present,  49;  extent,  48;  guide  to,  50; 
topography,  48;   vegetation,  49. 

Chickadee,  black-capped,  229. 

Chipmunk,  34,  196,  269,  274. 

Chordala,  2. 

Chub:  creek  (Sec  Horned  dace);  river, 
119. 

Cicada:   227;  nymphs,  262,  268. 
Circulation    of    water:      lake,    60,    61; 

pond,  136;   stream,  60. 
Cladocerans,  76,  83,  134,  173. 

Cladocerans      or     Cladocera,      scientific 

names: 
— Acropcrus  harpac,  134. 
— Bosmina,  76: 

obtusirostris,  134. 
— Ceriodap/inia,  134,  152: 

pulchella,  152. 

quadrangida,  152. 

reticidata,  134. 
— Chydorus  sphaericus,  134. 
■ — Daphne: 

hyalina,  76,  83. 

retrociirm,  76. 
— Daphnia.     See  Daphne. 
— Daphnidac,  278. 
— Diaphanosoma  brachyunim,  134. 
— Leptodora  hyalina,  76. 
— Macrothrix  rosea,  134. 


— PIciiroxiis  denlicidalus,  134. 
— Polyphemus  pcdicidus,  134. 
— Scapholeheris  miicronata,  134. 
—Simocephalits  scrrulatus,  134. 

Classification:  ecological,  2;  taxonom- 
ic,  2. 

Climate:  49;   former,  47. 

Climatic  communities,  38-41,  42,  49, 
50,310-15. 

Coloration,  25. 

Combinations  of  factors,  161-66. 

Communities:  basis,  t,t,,  34;  behavior 
in,  27;  classification,  37-41;  conver- 
gence, 309-12;  decline  of  primeval, 
13-16;  defined,  3;  man-made,  12-18; 
mapped,  ii;  of  buildings,  16;  of  culti- 
vated lands,  16;  of  forest,  189-261; 
of  forest  border  region,  39-41;  of 
forest  margins,  262-77;  of  large  lakes, 
73-85;  of  marshes,  169-80;  of  orchards, 
16;  of  ponds,  136-56;  of  prairies,  287- 
98;  of  roadsides,  12,  16,  275,  276;  of 
small  lakes,  125-35;  of  springs,  93; 
of  streams,  86-123;  of  thickets,  262- 
77;  relations  of  animals  in,  35,  70-71, 
166-68. 

Conditions  of  existence:  acjuatic,  58-72; 
terrestrial,  157-67. 

Consocies:  aphid,  37,  214,  234,  290; 
beech  log,  245-47;  defined,  37;  log, 
150-51;  pitcher-plant,  40,  193;  pool, 
39, 90;  spring,  39, 93;  temporary  rapids, 
39,  87,  88. 

Convergence  of  communities:  309-12; 
of  habitats,  93,  94. 

Coot,  170. 

Copepods:  fecundity  of,  35;  in  3'oung 
ponds,  173. 

Copepods,  scientific  names: 

— Canthocamptus  northmnbriciis,  206. 

— Cyclops,  278: 

albidiis,  134,  152,  206. 

biciispidatus,  76,  83. 

leuckarti,  83. 

prasiniis,  83. 

serrulatus,  134,  206. 

viridis,  152. 

viridis  amencaniis,  176,  206. 

viridis  brcvispinosiis,  134. 
— Diaptomus,  179,  278,  279: 

ashlandi,  83. 

leplopiis,  152. 

oregonensis,  83. 

reighardi,  135,  152. 

slagnalis,  176,  179,  1S5. 
— Epischura  lacuslris,  83. 


348 


ANIMAL  COMMUNITIES 


Correspondence  of  communities,  313-15. 

Cowbird,  274,  275,  290. 

Coyote,  IS,  167,  286. 

Crane-fly:  larvae,  190;  adults,  191. 

Crappie,  115,  120,  126,  140. 

Crayfish:     69,     70,     199;     behavior    in 

drought,  90. 
Crayfish,  scientific  names: 
— Cambarus: 

blandingi  aculus,  114,  116,  154. 
diogenes,  114,  121,  199,  204,  296. 
gracilis,  296. 
imtnunis,  144,  154. 
propinquus,  85,  90,   104,   114,   116, 
118,  121,  123. 

virilis,  85,  90,   105,   114,   116,   121, 
126,  135. 
Creeks,  sluggish,  102. 
Cricket,  striped  shrub,  266. 
Crickets,  167. 
Crossbill,  229. 
Crow,  242. 

Crustaceans  or  Crustacea:  67;  as  food, 
20;  pelagic,  76;  deep-water,  80.  See 
Entomostraca,  Crayfish,  Sowbugs,  Am- 
phipods.  Shrimps,  and  Mysis. 
Current:  water,  43,  61,  73,  86:  about 
stones,  61;  intermittent,  90;  swift, 
94-99;  reactions  to,  29,  34,  91. 
Cutworms,  hibernating,  201. 

Dace:  black-nosed,  91,  92,  106,  in,  115; 

horned,  90,  91,  106,  in,  115,  119, 120; 

red-bellied,  91,  in,  ii^,  119. 
Damsel-flies,  scientific  names: 
—Argia,  121: 

putrida,  116. 
— Calopteryx  maculata,  99,  105,  116,  118. 
—Enallagma,  117,  135,  155,  185. 
— Ischnura  verticalis,  104,  123,  132,  135, 

155- 
— Lestes,  155. 

Damsel-fly  nymphs,  99,  104,  105.  116, 
117,  118,  121,  123,  130,  132,  135,  15s, 
185. 

Darter:  34,  97;  banded,  95,  97,  119, 
120;  black-sided,  95,  97,  120;  Johnny, 
84,  91,  95,  105,  115,  119,  120,  126,  135; 
least,  84,  119;  rainbow,  95,  97,  119, 
120. 

Day  and  night,  responses  associated 
with,  30. 

Deep-water  communities  of  Lake  Michi- 
gan, 80. 

Deer,  14,  201,  238,  245,  269. 


Desmids,  76. 
Diatoms,  76. 
Dickcissel,  167,  283,  289. 
Digger-wasps,  habits  of,  222,  231. 
Dip-nets,  illegal,  57. 
Disagreement  of  communities,  307-8. 
Dissolved  foods  of  aquatic  animals,  58, 
Diurnal  depth  migration  of  Entomostraca 

and  rotifers,  77. 
Dogfish,  156. 
Dormancy:    of  eggs,  17 7-80 j    of  winter 

bodies,  129. 
Dragon-flies,  adult,  food  habits,  227. 
Dragon-flies,  scientific  names: 
—Aeschna,  118: 

constricta,  go,  114. 
— Aeschnidae,  104,  117. 
— Anax,  142: 

Junius,  132,  135,  155. 
— Basiaeschna  Janata,  121. 
— Celithemis  eponina,  155. 
■ — Cordulegaster  obliquus,  90,  114. 
— Epiaeschna  heros,  155. 
— Gomphus: 

exilis,  99,  116,  121. 

spicatus,  143,  155. 
— Leucorhinia,  142. 

inlacta,  146,  147,  155. 
— Libelhda  pulchella,  155. 
— LibeUulidae,  104. 
—Macromia  taeniolata,  103,  123. 
— Pachydiplax  longipennis,  155. 
• — Plathemis  lydia,  116. 
— Tetragoneuria  cynosura,  114,  135. 
— Tramea,  142: 

lacerata,  155. 
—Sytnpetrum,  155: 

rubicundulum,  155. 
Dragon-fly  nymphs,  90,  93,  99,  103,  104, 
116,  117,  118,  121,  123,  132,  135,  142, 
143,  146,  147,  155. 
Drift,  animal,  219. 

Droughts:      90;      behavior    of     stream 
animals    in,    92,    105;     force    animals 
downstream,  106. 
Duck,  wood,  181,  190,  191. 
Dunes,  moving,  229. 

Earthworms,  20,  190,  262,  269. 
Ecological  agreement:    of  communities, 

305;  of  individuals,  plants,  and  animals, 

304-8;   of  species,  315. 
Ecological  equivalence,  34. 
Ecology:      content     of,     32,     299-318; 

genetic,    113,    137,    247-52,    308-15; 


INDEX  OF  SUBJECTS 


349 


E  cology — Coniin  md: 

organization  of,  23,  25,  32,  2,2>\  physio- 
logical, 299-308;  relation  to  biology, 
315-18;  relation  to  geography,  318-20; 
relation  to  sociology,  318. 

Economic  problems:   9-1 1;   preservation 

of  breeding,  grounds  of  fishes,  1 26. 
Eel,  84. 

Egg-laying,  of  aquatic  insects,  107,  108. 
Electricity,  161. 
Elk,  14,  201,  269. 

Elm:  American,  190;  coxcomb  gall  of, 
192. 

England:  bird  protection  in,  8;  man- 
made  nature  in,  11. 

Entomostraca,  20,  69,  70,  71,  76,  133,  152, 
176,  179,  204;  {see  Cladocerans, 
Copepods,  and  Ostracods);  the  food 
of  young  fishes,  76. 

Environment:  42-56,  58-67,  157-66; 
299;  factor  of,  42-44;  relation  to, 
22-33. 

Equilibration:  of  aquatic  communities, 
diagram  illustrating,  70;  of  land 
communities,  166-69;  diagram  illus- 
trating, 167. 

Erosion,  important  on  clay  bluffs,  209, 
210. 

Ethology,  32. 

Evaporation:  162-65;  effect  upon 
animals,  162-63;  expression  of  con- 
ditions, 162;  of  different  habitats, 
164;  in  forest  stages,  248-49;  reactions 
to,  and  death  by,  163. 

Evaporimeter:  Piche,  164;  porous  cup, 
162. 

Factors  in  distribution,  299. 

Fairy  shrimp,  177-79,  185,  278-79. 

Field  study:  legal  aspects,  56;  methods, 
321-24. 

Fish:  breeding  of,  126;  destroyed  by 
lampreys,  219;  feeding,  130;  longi- 
tudinal distribution  in  streams,  109, 
no,  115,  119,  120;  protection,  56,57; 
traps,  80. 

Fish,  scientific  names: 
— Abramis,  65: 

crysoleucas,  102,  115,  119,  120,  142, 

143,  156. 
— Acipenser  riibictindus,  85. 
— Ambloplites  rupestris,  85,  99,  119. 
— ^4  meiurus: 

lacustris,  85. 

melas,  102,  119,  120,  149,  156. 


natalis,  156. 
nebulosus,  156. 
— Amia  calva,  156. 
— An^uiUa  rostrata.  84. 
— Aphredoderus  sayanus,  120. 
— Aplodinotus  grunniens,  85. 
— A  rgyrosomus: 
artedi,  82,  84. 
hoyi,  81,  82,  85. 
nigripinnis,  81,  82. 
prognathus,  79,  80,  82,  85. 
— Boleosoma  nigrum,  84,  91,  95,  105,  115, 

119,  120,  135. 
— Campostoma  anomalum,  119,  120. 
— Carpiodes,  85. 
— Catostomus: 

catostomus,  84. 

commersonii,  84,  gi,  92,   106,    115, 
119,  120. 

nigricans,  84,  119. 
— Chaenobrytlus  gulosiis,  142,  156. 
— Chrosomus  erythrogaster,  91,  in,  115, 

ng. 
— Coregonus  clupeiformis,  82,  85. 
— Crislivonier  namaycush,  79,  82,  85, 
— Cyprinus  carpio,  120. 
— Erimyzon  sucetta,  115,  119,  142,  156. 
— Esox: 

lucius,  85,  115,  120,  140. 
vermiculatus,  105,  115,  142,  156. 
— Etheostoma: 

coeruleum,  95,  97,  119. 
flabellare,  95,  97,  119. 
zonale,  95,  97,  119,  120. 
—Eucalia  inconstans,  85. 
— Eupomotis  gibbosus,  84,  156. 
— Funduliis: 

diaphanus  menotia,  84,  123. 
dispar,  120,  132,  135. 
notatus,  119. 
— Hadropterus  aspro,  95,  97,  120. 
— Hiodon: 

alosoides,  85. 
tcrgisKS,  85. 
— Hybopsis  kenluckiensis,  119. 
—Labidesthes  sicculus,  85,  130,  135. 
— Lepisosteus  osseus,  85. 
— Lepomis: 

cyanelliis,  102,  119,  120,  128,  156. 
megalolis,  99,  119. 
pallidus,  84,  99,  115,  119,  120,  156. 
— Lota  maculosa,  82,  85. 
— Microperca  punctidata,  84,  119. 
— Micropterus: 

dolomieu,  85,  99,  119,  120. 
salmoides,  85,  115,  120,  128,  156. 
— Moxostoma: 

aurcolum,  84,  115,  119,  140. 
breviceps,  120. 


350 


ANIMAL  COMMUNITIES 


Fish — Continued: 
— Notropis: 

atherinoides,  84. 

blenniiis,  84,  119,  127,  135. 

cayuga,  115,  119,  140. 

cornutus,  115,  119,  120,  140. 

hiidsonius,  84. 

rubrifrons,  119. 

umbratilis,  119,  120. 
— Noturiis  Jlaviis,  119. 
— Perca  Jiavescens,  85,  99,  119,  120,  126, 

156. 
— Percopsis  guttalus,  84. 
— Phenacobiiis  mirabilis,  119. 
— Pimephales: 

notatus,  84,  91,  115,  119,  120. 

promelas,  115. 
— Pomoxis: 

annularis,  115,  140. 

sparoides,  120. 
■ — Rhinichthys  atronasus,  91.  93,  106,  in, 

115- 
— Schilbeodes: 

exilis,  95. 

gyrinus,  85,  105,  119,  142. 
— Semotilus  alromaculatus,  91,   106,  in, 

115,  119,  120. 
— Stizostedion  vitrcum,  85. 
— Triglopsis  thompsoni,  81. 
— Umbra,  65: 

limi,  84,  119,  120,  142,  143,  149,  156. 
Fisher,  196. 

Flatworms:     brown    cigar-shaped,     174; 
green,  176,  179;  vernal  planarians,  176. 
Flatworms,  scientific  names: 
— Dendrocoelum,  118,  172. 
— Mesosloma,  174,  185. 
— Planaria: 

dorotocephala,  118,  172. 

maculata,  135. 

velata,  176,  185,  278. 
— Vortex,  176,  179: 

viridis,  185,  278. 
Flesh-flies,  119. 
Flicker,  274,  275. 
Flies,  or  diptera,  scientific  names: 
—Anthomyidae,  284. 
— Asilus,  285. 

—Bibio  albipennis,  266,  268. 
— Bombylius  major,  232. 
— Cecidomyia: 

verrucicola,  192. 

viticola,  191. 

vitis-pomiim,  191. 
— Chlorops  sulphurea,  284. 
• — ■Chrysomyia  macellaria,  186. 
— Chrysops: 

aestuans,  188. 

callidus,  188. 


— Coenomyia  ferruginea,  271,  277. 

— Coenosia  spinosa,  285. 

• — ■Cynomyia  cadaverina,  186. 

— -Dasyllis,  270. 

— DoUchopodidae,  284,  297. 

— Drosophila  amoena,  207. 

— Drosophilidac,  284. 

— -Erax,  224. 

— Eristalis  tenax,  214,  270,  272,  293,  297, 

298. 
— Exoprospa,  223,  224. 
— Hclobria  hybrlda,  272,  277. 
— Helophilus  conostoma,  285. 
— Loxocera  pcdoralis,  208. 
— Mesogramma,  292. 

geminata,  297. 

marginata,  188,  205. 

poliia,  292. 
— Milesia  virginicnsis,  259    271,  272. 
— Mtiscidac,  219. 
■ — ■Mycrtophilidae,  217,  247. 
— Osinidac,  284. 

— Pachyrhina  ferruginea,  256,  277,  285. 
— Paragus  angustifrons,  285. 
— Pipunculus  fuscus,  280. 
— Promachus  vertebratus,  222,  224. 
— Psilidae,  208. 
— Psilopodiuus  sipho,  270. 
— Sapromyza  philadclphica,  239.  257. 
— Sarcophaga,  186. 
• — Sarcophagidae,  219. 
— -Sciara,  217. 
— Sciomyzidae,  204,  284. 
■ — Scoliocentra  ,279: 

helvola,  280. 
• — -Sepedon  pusilliis,  204. 
— Sparnopolius  flavius,  285. 
— Spilogaster,  281. 
— ■Spilomyia  longicornis,  261. 
— Spogosiylum  anale,  229,  230,  234,  252. 
— Siraussia  longipcnnis,  40,  272,  277. 
— Syritta  pipiens,  285. 
— Syrphus: 

americanus,  202. 

ribcsii,  214. 
—  Tabanidac,  170. 
— Tabanus  lineola,  281. 
• — Tctanocera,  170,  188,  279: 

combinata,  188. 

plumosa,  188,  197,  284. 

saratogensis,  188. 

umbrarum,  188,  280,  284,  297. 
• — ■Tipulidae,  206. 
— Tritoxajiexa,  285,  297. 

Flood-plain  communities,  197-204. 

Floods:  105;  insects  in,  203;  mammals 
in,  202;  mixing  of  communities  by, 
105;  upstream  migration  during,  106, 
107. 


INDEX  OF  SUBJECTS 


351 


Fly  larvae,  scientific  names: 

— Ceratopogoii,  148,  155. 

— Chirouomidae,  103,  187,  191. 

— Chironomus,  93,  96,  99,  116,  117,  118, 
123,  134,  142. 

— Corethra,  125. 

— Dixa,  93,  118. 

— Melriootcmis,  83,  84. 

— Pcdicia  albivilta,  114. 

— SimuUum,  87,  88,  93.  105,  114,  116,  118. 

— Stratiomyia  ,123. 

— Tabanus,  116. 

— Tanypus,  93,  118,  148,  155. 

Fl\'catcher:  Traill's,  190;  great  crested, 
196,  244. 

Food:  factor  in  distribution,  299; 
emphasized  by  paleontologists,  299;  of 
young  fishes,  76,  142,  144;  relations: 
aquatic,  65-72,  terrestrial,  166-68. 

Forest  communities:  189-261;  clay,  210- 
17;  dry,  209-33;  flood-plain,  197-203; 
mesophytic,  233-47;  rock,  217-18; 
swamp,  189-93;  sand,  218-33;  sum- 
mary of,  250-51;  tamarack,  193-97; 
wet,  189-200. 

Forest  margin  communities,  262-75. 

Form,  relation  to  function,  22. 

Formations,  defined,  38.  See  Communi- 
ties. 

Fo.x:  gray,  15,  237,  245;  red,  201,  236, 
237,  245. 

France:  bird  protection  in,  11;  Phyl- 
loxera in,  191. 

Frog:  173;  bull,  171;  common,  156,  169, 
195,  296;  cricket,  135,  169,  296;  green, 
169,  171,  195;  swamp  tree,  195,  206, 
283,  296;  tree,  205,  234;  tree  (Picker- 
ing's), 194,  195,  196,  207,  234,  244, 
253;    wood,  195,  206,  207,  243,  244. 

Function,  relation  to  form,  22. 

Gall  flies,  40,  191,  272,  277. 

GaUinule,  Florida,  171. 

Gar,  long-nosed,  85. 

Garter-snake,  167. 

Gas-bubble  disease  of  fishes,  60. 

Geology,  surface  in  young  stream,  8. 

Gland,  silk,  95. 

Glenwood  beach,  46. 

Goldfinch,  268,  274;    American,  199,  274.^ 

Gopher,  pocket,  167,  288. 

Gordiics,  loi. 

Grape:     apple  gall   of,    191;     free    from 


Phylloxera  in  wet  soil,  190;   tube  gall      — Aphrophora,  202: 
of,  191;   wart  gall  of,  191.  '^^      4-noiata,  267. 


Grasshoppers:     167,    long-horned,    227; 

maritime,  223-25. 
Grebe,  pied-billed,  132. 
Green  snake,  289. 
Grossbeak,  pine,  229. 
Ground  beetles,  180. 
Grouse,  ruffed,  196,  227. 
Guide  to  Chicago  region,  50. 

Habitat:  preference,  3 1 ;   selection,  34. 
Hair-worm  (Gordius),  loi. 
Hare,  varying,  15,  191,  195. 
Harvestmen,  scientific  names: 
— Liobunum: 

dorsatum,  202,  205,  208. 

grande,  204,  298. 

nigropalpi,  244,  253. 

ventricosum,  202,  208. 
• — Oligolophus  pictus,  244,  261. 
Hawk:  marsh,  167;  night,  167,  289;  red- 
shouldered,  242;  red-tailed,  242;  sharp- 
shinned,  274,  275;   sparrow,  274,  275. 
Hcmiptera  (true  bugs),  aquatic,  scientific 

names: 
— Belostoma,  65,  131. 

amcricana,  148. 
■ — Belostomidae,  65,  151. 
— Benacus,  131. 

griseus,  148. 
— Buenoa,  132: 

plalycnemis,  135,  148,  155. 
—Corixa,  104,  117,  123,  155. 
— Xolonecla,  117,  132: 

loidulata,  135,  148,  155. 

variabilis,  123,  135,  148,  155. 
— Notonectidae,  151. 
— Pelocoris  femoratus,  104,  123. 
— Plea,  132: 

striola,  148,  155. 
— Ranatra,  65,  131,  151. 

fusca,  104,  123,  155. 

kirkaldyi,  155. 
— Zaitha,  65. 

fluminea,  104,  116,  123,  135,  148,  155, 

185. 
Hemiplera.  terrestrial,  scientific  names: 
—Acanthocephala  terminalis,  241,  257. 
— Acholla  mullispinosa,  199,  208. 
— Adelphocaris   rapidus,    188,    214,    264, 

266,  276,  292,  297. 
— Agallia  4-punctata,  298. 
.  —Alydiis  conspersus,  292,  297. 
f^^—Amphiscepa  bivittata,    188,    199,    208, 
29: 


352 


ANIMAL  COMMUNITIES 


V 


Hemipkra — Continued: 

— Athysanus: 

striolus,  297,  298. 
parallelus,  297. 
/  — Banasa  calva,  261. 
^'-^    — Campylenchia  cur  vat  a,  292,  297. 
^^- — Cercopidae,  204,  261. 
v^-^  — Ceresa: 

borealis,  206. 

bubalus,  265,  276,  284,  292. 
— Charksterus  antennator,  259. 
— Chlorotetlix: 

spatulata,  298. 
rytergata,  297. 
.  6  unicolor,  297. 
)^' '"  — Cicada  linnei,  260. 
— Cicadula: 
0    6-notata,  283,  297. 
(5   variata,  206. 
^  — Clasloptera: 
v/  obtusa,  261. 

ly'  proteus,  277. 

— Colopha  ulmicola,  192. 

— Corynocoris  distinctus,  276. 

— Corythiica  arcuata,  233. 

— Cosmopepla  carnifex,  187,  188,  298 

— Cymiis  angustatits,  188. 

■ — Diedrocephala  coccinea,  277. 

— Diplodus  luridus,  228 

^  —Empoasca  niali,  188,  298. 
I,      — Enchenopa  binotata,  274. 
— Euschistus: 

fissilis,  264,  276. 
tristigimus ,  205,  241,  260,  264. 
variolarius,  259,  298,  306. 
/    — Eutettix  straminea,  298. 
— Garganus  fusiforniis,  298. 
— Gargaphia  tiliae,  244,  261. 
— Gelastocoris  oculatus,  180,  185,  186, 
^, — Gypona: 

octolineata,  206,  261. 
striata,  206. 
— Halticus  uhleri,  292,  298, 
>_/    — Helochara  communis,  297. 
— Horcias: 

goniphoriis,  292. 
marginalis,  298. 
— Hyaliodes  vitripennis,  41,  234,  235, 
U     — Idiocerus  snowi,  208. 
— Ilnacora  stalii,  277. 
— Ischnodemus  f aliens,  188. 
t^  — Jassus  olitarius,  261. 
i^ — Lepyronia  quadrangular  is,  204,  208 
— Lygus: 

plagiakts,  206. 

pratensis,   198,   208,   257,   263, 
292,  306. 
— Macrosiphum  granaria,  290. 
r^    — Megamelus  marginatus,  277. 


^     -   Draeculacephalamollipes,  i8S,  28^, 


— Miris  dolobrata,  292,  297. 
— Neides  muticus,  263,  276. 
— Neuroctenus  simplex,  231,  269. 
— Nezara  hilaris,  199,  208,  257. 
0 — Ormenis  pruinosa,  191. 
^~~  — Otiocerus  degeeri,  259. 
^^  — -Paraholocratus  viridis,  188. 
— Pelogonus  americflmis,  204. 
— Pemphigus: 

imbricalor,  244,  245. 
populicaulis,  225,  258. 
vagabundus,  225,  258. 
— Pentagramnia  vittatifrons,  204. 
— Penlatomidae,  261. 
I-  ^     — Phihno)iia  hilineata,  187. 
j[) — Phlepsius  irroratus,  259. 
— Phylloxera,  190,  243,  273: 
caryae-caulis ,  260. 
vastratrix,  191,  273. 
—Phymata  erosa  fasciata,  187,  264,  276, 

293,  297. 
— Physatochila  plexa,  188. 
— Plagiognathus: 
fuscosHS,  208. 
politus,  298. 
1/  — Platymetopius  acutus,  298. 
—Podisus  maculiventris ,  257,  277. 
— Poecilocapsiis  lineatus,  206,   270,   272, 

276,  277. 
— Protenor  belfragei,  276. 
— Reduviolus: 

annulatus,  208,  260,  202,  239. 
ferns,  187,  283. 
subcoleoptratus,  217. 
— Salda: 

coriacea,  296. 
humilis,  180. 
— Saldidae,  180,  219. 
V     - — Scaphoideus: 

*"     auronitens,  239,  260. 
f-j    immistus,  206. 
— Schizoneura,  273. 
V-^  —Scolops  snlcipes,  263,  265,  276. 
(^  — Stictocephala  lutea,  297. 

— StiphrosOma  stygica,  276. 
1/^  — Telemona  querci  (monticola),  259,  233, 

234- 
— Teratocoris  discolor,  297. 
— Thyreocoris: 

pulicaria,  298. 
unicolor,  187. 
— Thyreocoris  unicolor,  187. 
— Trigonotylus  ruficornis,  298. 
— Triphleps  insidiosus,  259,  306. 
U     — Typhlocyba  querci  bifasciata,  233,  259. 
Heron,  green,  181,  192. 
266,      Herring:  lake,  82,  84;  toothed,  85. 

Hibernation  groups:  of  beetles,  192-93; 
of  snails,  192;  of  flood-plain  animals, 
201-2. 


297. 


260. 


INDEX  OF  SUBJECTS 


353 


History:      of     Chicago     region,     13-15; 

geological,  45-48. 
Hog-nosed  snake,  231. 
Hornet,  white-faced,  hibernation  of,  192. 
Homtails,  217. 
Humus  in  soil,  158. 
Hydra,  107,  131. 

Hymenoptera:  scientific  names: 
— Agapostemo)i: 

splendcns,  232,  259. 

viridulus,  297. 
— Ammophila,  231: 

nigricans,  285. 

procera,  231. 
— Andrenidac,  224,  255. 
— Andricus  seminator,  234,  260. 
— Anomoglossus  pusillus,  188. 
— Anoplius: 

divisus,  222,  252. 

marginaUis,  255. 
— Apidae,  224. 
— Apis  melUfera,  214. 
— Augochlora: 

confusa,  187,  252. 

ptira,  239,  256. 
— Bembex  spinolae,  222,  223,  252. 
—Bombus: 

americanorum,  214. 

separaliis,  290,  297. 
— Ceropalidae,  255. 
— Chloralichis  cressoni,  277. 
— Cimbex  americana,  208,  267. 
— Coeloixys  rufitarsus,  231,  255. 
— Crabro  iiiterruptulus,  277. 
— Dielis  phimipcs,  222,  252. 
— Epeolus: 

cressonii,  285. 

pusillus,  231,  253. 
— Eumenes  fraternus,  266,  276. 
— Eiimenidae,  255. 
— Halictus  nelumbonis,  255. 
— Ichneumon: 

extrematatus ,  192. 

galemis,  192,  297. 

niendax,  191,  192. 

zebratus,  285. 
— Ichneumonidae,  261. 
— Larridae,  255. 
— Microbembex,  223: 

monodonta,  222.  223,  252. 
— Mutilla  ornativentris,  222,  252. 
— Netnatinae,  205. 
— Odynerus: 

anormis,  231,  255. 

//I'm,  276. 
— Paniscus  gemminatus,  285. 
— Pelopoeus  cementarius,  214,  254. 
— Pinipla: 

conquisitor,  214. 

inquisitor,  191, 


— Plesia  inlerrupta,  255. 
— Polistcs,  241,  266: 

variaiiis,  276,  297. 
— Pteronus  veniralis,  667. 
— Sceiipron  cementarius,  285. 
— Scoliidae,  255. 
— Specodcs  dichroa,  231,  252. 
— Tachytes  iexanus,  255. 
— Thalessa  atrata,  261. 
— Trogus  vulpinus,  261. 
— Tiphia  vulgaris,  286,  289,  290. 
— Vespa  maculata,  192,  202,  256. 
— Xiphydria  maculata,  207. 

Ice-sheet:  Wisconsin,  45;  advance  and 
retreat,  43-46;  drainage  from,  45, 
46. 

Indians,  13. 

Insects:  carriers  of  disease,  21;   enemies 

of,  9,  10;  human  food,  21. 
Inter-mores  physiology,  34,  35. 
Inter-physiology,  34,  35. 
Isle  Royale,  195. 
Isopods.     See  Sowbugs. 

Lacebugs,  232. 

Lake:  Chicago,  45-47;  Geneva,  62-63; 
Michigan,  area,  73,  bottom  communi- 
ties, 78-81,  communities,  73-85,  condi- 
tions, 58-65,  Hght,  63,  pressure,  64, 
temperature,  62,  species,  83-85;  On- 
tario, 78;   Pine,  67;   Turkey,  67. 

Lake  communities,  73-85,  124-36;  sum- 
mary concerning,  large  lake,  81,  small 
lake,  128,  131. 

Lake  herring,  77. 

Lakes:  circulation  in,  60;  distinguished 
from  ponds,  124. 

Lampreys,  219. 

Larch  or  tamarack:    sawfly,  195;  lappet 

moth,  195;  woolly  aphid,  195. 
Lark:    bunting,  286,  289;     horned,  167, 

289;    meadow,   167,   283,   289;    shore, 

286. 

Larvae:  lepidopterous,  167;   sawfly,  167. 
Laws:    minimum,  68;     toleration,  302; 

limit  of  range,  304;    distribution  area, 

304- 
Lawyer,  82,  85. 
Leaf-beetles,    long-horned    aquatic,    65, 

123,  ^iS,  151- 
Leaf-bugs,  hibernating,  202. 
Leeches:    in  Lake  Michigan,  77,  80,  83, 

84;     in    lakes    and    ponds,     129;    in 

streams,  loi,  103. 


354 


ANIMAL  COMMUNITIES 


Leeches,  scientific  names: 

— Clcpsine,  84. 

— Dina  fcrvida,  153. 

—  Erpobdclla  punctata,  153. 

■ — Glossiphonia: 

fitsca,  123,  153. 

hctcrocUla,  153. 

stagnalis,  83. 
— Haemopis: 

graudis,  103,  121,  153. 

marmoratis,  153. 
— Macrobdclla  decora,  135,  151,  153. 
— Placobdella: 

parasitica,  135,  148,  150,  153. 

rugosa,  117.  153. 
Lepidoptcra,  scientific  names: 
— Acroitycta  oblinita,  188,  267. 
— Agrotis  ypsilon,  285. 
— Alypia  octomacidata,  273. 
— Ampclophagiis  myroii,  268. 
— Anisota-  scnatoria,  241,  260. 
■ — Anthocharis  genutia,  257. 
— Apantesis  phalterta,  285. 
— Basilarchia  archippus,  251. 
— Cerura,  232,  259,  279. 
— Datana,  199: 

angnsii,  260. 
— Diacrisia  virginica,  285. 
—Estigmeiia  acraca,  284,  285. 
— Evetria  comslockiana,  228,  229,  258. 
• — Gcomctridae,  205. 
• — Halisidota,  238,  260. 
— Hemilcuca  maia,  188,  268,  276. 
— Heterocampa  gitttivitla,  259. 
— Hydria  uiidulala,  260. 
• — Isia  isabella,  285. 
— Leucania  unipuncla,  285. 
— Nadata  gibbosa,  231,  233,  259. 
— Noctuinae,  204. 
■ — Papilio: 

ajax,  244. 

cresphontes,  268,  276. 
iroilus,  244. 
— Pier  is  protodice,  220,  222. 
— Prionoxystus  robiniae,  267. 
— Psychomorpha  epimensis,  273. 

hunt  era,  270. 

cardui,  270. 
—Satnia  cecropia,  199. 
— Scepsis  fulvicollis,  170,  284,  297. 
• — Schizura,  268. 
— Symmcrista,  199: 

albifrons,  200,  260. 
Licenses  to  collect  animals,  57. 
Liebig's  law  of  minimum,  68. 
Life  histories:    physiological,  33;    repre- 
sented as  circles,  71. 


Light:    intensity,   159-60;    necessity  for 

food  supply,  66;   penetration  in  water, 

63;   reactions  to,  29,  251. 
Limnetic  communities,   74-77,  103,  125, 

140. 
Living  substance,  22. 
Lizard,  six-lined,  227. 
Localities  studied,  52-56. 
Locust:    lesser,   227;    long- horned,   227; 

lubbery,     262;      mottled    sand,     227; 

narrow- winged,  227;   sand,  227. 
Logs:     lake,    131;     in   ponds,    150;     in 

streams,  10 1. 
Long- jaw,  79,  80,  82,  85. 

Maggots,  219. 

Mallard,  171. 

Mammalia,  2. 

Mammals,  economic  value  of,  9,  10. 

Mammals,  scientific  names: 

— Bison  bison,  289. 

— Blarina  brevicauda,  201. 

— Canis  latrans,  286. 

— Citellus: 

franklini,  269. 

13-lineatus,  228,  255,  286. 
-^Fiber  zibethictis ,  156. 
— Geomys  bursarius,  288. 
— Hominidae,  2. 
— Homo  sapiens,  2,  319. 
— Lepus  americanus,  191,  195. 
— Lutra  canadensis,  195,  199. 
— Lynx  rufus,  242. 
— Marmota  monax,  215,  253. 
— Maries: 

americana,  196. 

pennanti,  196. 
— Mephitis  mesomelas  avia,  269. 
— Microtus: 

ochrogasler,  289. 

pennsylvanicus,  282. 
— Mustela: 

noveboracensis,  201. 

vison  lulreocephala,  191. 
— Odocoileus  virginianus,  238. 
— Peromyscus: 

bairdii,  286. 

leucopus  noveboracensis,  201,  236. 
— Primates,  2. 

— Sorex  personalus,  189,  201,  275,  269. 
— Tamias  striatus  griseus,  269. 
— Taxidea  taxus,  288. 
— Urocyon  cinereoargentcus,  237. 
— Vulpes  fulvus,  236. 
— Zapus  hudsonius,  269. 
Man,  relation  to  animals,  5-20. 


INDEX  OF  SUBJECTS 


355 


Maps:  evaporation,  50;  frontispiece,  ii; 
guide,  (facing)  52;  list  of,  48;  vegeta- 
tion, 51. 

Marsh  communities,  169-73. 

^Marten,  pine,  196. 

IMaterials    for    abode,  of   land  animals, 

157- 
May-flies,  65,  170. 

IMay-flies  or  Ephcmerida,  scientific  names: 

— Bad  is,  93. 

— Caeuis,  114,  123,  155. 

— Callibaclis,  104,  123,  130,  135,  155. 

— Chirotenctes  siccus,  117. 

— EphcmcrcUa  cxcrucians,  135. 

— Ephemcridac,  78. 

— Heptagcnia,  93,  118. 

— Heptagcninac,  96,  105,  114. 

— Hcxagenia,  39,  103,  107,  117,  123. 

— Siphlurus,  96,  142,  155: 

aUernatiis,  98,  116. 
May-fly  nymphs,  88. 
JMetallic  wood-borers,  191. 
Methane,  59,  60. 

Midge  larvae:     69,   80,    129,   130;     an- 
aerobic, 133.     Sec  Fly  larvae. 
Midges,  170. 
Miller's  thumb,  126. 
Mimicry,  25. 

Mineral  matter:  excessive  in  springs, 
93;  necessarj^  to  life,  58. 

Mink,  15,  171,  191. 

Minnow:  blackfin,  119,  120;  black- 
head, 115;  blunt-nosed,  79,  84,  115, 
119,  120,  126;  Cayuga,  115,  119,  140; 
mud,  65,  84,  119,  120,  143,  149,  156; 
ruby  faced,  119;  shiner,  84;  straw- 
colored,  79,  84,  126,  127,  135;  sucker- 
mouthed,  119. 

Mites,  aquatic,  egg-la3'ing  of,  129. 

Mites,  aquatic,  scientific  names: 

— Hydrachna,  ij-j,  185. 

— Limnocharcs  aquaticus,  130,  144. 

IMites,  terrestrial,  scientific  names: 

— Trombidiiim,  190: 
sericeiim,  207. 

Moisture:  equivalent  of  soil,  158;  re- 
lation to  wilting  coeflicient,  158. 

Mole  cricket,  18  r. 

Moles:   167,  238;   star-nosed,  282. 

Molliisca,  80,  106,  144.  See  Snails; 
Mussels;  Sphaeridae. 

Moon,  influence  of,  on  plankton,  67. 

Moon-eye,  85. 

Mores,  defined,  32. 


Mosquito:  eaten  by  fishes,  132;  fringe- 
legged,  174;  marsh,  174,  176;  smoky, 
178,  180. 

Mosquitoes,  scientific  names: 

— Aedes  fiisca,  17S. 

— Anopheles,  114: 

punctipennis,  iy6. 

— Culex  canadensis,  193,  206. 

— Culicidae,  185,  191. 

— Wyeomyia  smithii,  193,  204. 

Mourning  dove,  269,  274,  275. 

Mouse:  Cooper's  lemming,  195;  deer, 
167;  field,  167,  289;  food  of  marten, 
196,  of  skunk,  269,  of  shrews,  269; 
meadow,  282;  white-footed  wood, 
201,  237;  jumping,  269,  274. 

Mud  puppy,  130. 

Muskrat,  14,  130,  156,  140,  143,  151, 
171. 

Mussels:   70;   stunted  on  humus,  129. 
Mussels,  scientific  names: 
— Alasmidonta  calceola,  99,  100,  116,  121. 
— Anodonta: 

grandis,  83,  103,  104,  126,  153. 

grandis  footiaua,  143,  153. 

marginata,  83,  126,  135,  140,  153. 
— A  nodonloides: 

ferussacianus,    39,  99,  100,  108,  117, 

127. 

ferussacianits  subcylindraceiis,  100. 
— Lampsilis: 

ellipsiformis,  117,  121. 

iris,  117. 

ligamentina,  99,  117,  123. 

luleola,  99,  103,  117,  121,  122,  123, 

126,  129,  135,  140,  153. 

ventricosa,  99,  117,  122. 
— Quadrula: 

rubiginosa,  103,  117,  122,  123. 

inidnlala,  103,  117,  121,  122,  123. 
— Uiiio  gibbosns,  103,  117,  122,  123. 
— Unionidae,  146,  153. 
■ — Symphynota : 

complanata,  122. 

costata,  122. 

INIyriopods,  viii,  215. 

Myriopoda,  scientific  names: 

— Fontaria  corrugate,  215,  236,  237,  243, 

253,  254. 
— Geophilus,  200,  254. 

riibens,  217,  239,  243,  253. 
— Litlwbius,  187,  191,  234,  239,  254. 
— Lysiopetalum  lactarium,  217,  239,  253 

254. 
— Polydesmidae,  215. 
— Polydesmus,  191,  205,  206,  234. 
— Scytonotus  granidatus,  206. 


356 


ANIMAL  COMMUNITIES 


Myriopoda — Continued: 

— Spirobolus  marginatiis,  201,   236,   237, 

243,  253. 
My  sis  relicta,  80,  81,  85. 

Natural  selection,  25. 

Nature:  5,  6;  man  and,  8-20;  man- 
made,  8;  state  of,  7;   struggle  in,  7. 

Neiiroptera,  scientific  names: 

■ — Chauliodes,  123. 

rasiricornis,  145,  148,  150,  155. 

— Chrysopa: 

albicornis,  297. 
oculala,  214,  291. 
rufialbris,  261. 

— CorydaUs  cornitta,  116,  121. 

■ — Cryptoleon  ncbulosnm,  283. 

— Mantispa  brunnca,  273,  274. 

— Sialis,  121. 

Newt,  121,  149,  156. 

Nitrates,  66. 

Nitrogen:  59,  60;  cause  of  gas-bubble 
disease,  60;  in  lakes,  125;  in  spring 
water,  93. 

Number  of  individuals,  relation  to  area 
of  optimum,  303. 

Onion-fly,  293. 

Optimum,  range  of,  300-305. 

Oriole:     Baltimore,    274,    275;     orchard, 

274. 
Orthoptera,  243,  272,  285,  292,  306. 
Orthoptera,  scientific  names: 
— Acrididae,  187,  204. 
— Ageneoletlix  arcttosus,  227,  252. 
— Amblycorypha,  205: 

oblongifolia,  208,  266,  267,  276. 

rotiindifolia,  272. 

tihleri,  241. 
— Apilhes  agitator,  268. 
' — Apterygida  acideata,  194,  205. 
• — Atlanticus  pachymerus,  239,  260. 
— Ceiithophilus,  205,  237,  239,  243. 
■ — Chloealtis  conspersa,  232,  259. 
— Conocepltalus: 

ensiger,  232,  259,  298. 

nebrascensis,  264,  276. 

robustus,  265. 
— Cyrtophiilus  perspicillatus,  241,  260. 
— Diapheromera  femorata,  187,  235,  241, 

257- 
— Dissosteira  Carolina,  198,  214,  218,  254. 
— Gryllus  pennsylvanicus,  218. 
— Hippiscus  tuberculatiis,  255. 
—Ischnoptera: 

inaequalis,  218. 

major,  218. 


— Melanoplus: 

angustipennis,  2 it,  252. 

atlanis,  225,  228,  252. 

bivittatus,  198,  218,  276,  285,  297. 

diferentialis,  266,  276. 

fetnur-rubrmn,    187,    214,    218,    223, 

276,  285,  296. 

punctidatiis,  194,  195,  205. 

viridipes,  297. 
• — Nemobius: 

fasciatus  vitlalus,  298. 

maculatus,  263,  297. 
— Neotettix  hancocki,  190. 
— Oecanthus: 

angustipennis,  241,  260,  272. 

fasciatus,  232,  257,  272,  276. 

nivens,  272. 
— Orchelimum: 

glaberrimum,  204,  208. 

indianense,  276. 

vulgare,  292,  296,  298. 
• — Orphidclla  speciosa,  297. 
— -Paralettix  cucidlalus,  181,  186. 
— Paroxya  hoosieri,  204. 
— Psinidia  fenestralis,  223,  225,  252. 
— Schistocerca  rubiginosa,  232,  257. 
— Scudderia,  214,  217: 

furcata,  241,  266,  267,  276. 

texensis,    232,    259,    266,    277,    293, 

297,  298. 
— Sparagemon  wyomingianum,  228,  252. 
— Stenobothrus,  170: 

curtipennis,  188,  204,  266,  285,  296, 

298. 
— Tettigidea: 

armata,  181. 

parvipennis,  181,  282. 

pennata,  236,  282. 
— -Tcttix  obscura,  190. 
— Trimcrotropis  maritima,  223,  252. 
• — Xiphidium,  170: 

brevipenne,  188,  208,  263,  266. 

ensijeruin,  215. 

fasciatum,   39,    188,    263,    264,    284, 

285,  296. 

nigropleura,  263,  276. 

strictum,  232,  259,  292,  293,  298. 
Osprey,  226. 
Ostracods,  129. 

Ostracods  or  Ostracoda,  scientific  names: 
— Cypria  exsculpta,  152. 
— Cypridopsis  vidua,  130,  152. 
—Cypris  fuscata,  185. 
— Cyprois  marginaia,  177,  179,  185. 
—Notodromds  mondcha,  144. 
■ — Ostrdcoda,  144. 
— Potdmocypris  snidragdiud,  134. 

Otter,  19s,  199. 
Oven-bird,  244. 


INDEX  OF  SUBJECTS 


357 


Owl,  screech,  229. 

Oxygen:  anaerobic  animals,  133;  bur- 
rowing dragon-fly  nymphs,  142;  circu- 
lation of,  61;  correlated  with  age  of 
ponds,  68-70;  in  lakes,  125,  133;  in 
pools,  91;  in  springs,  93;  in  streams, 
103;  intermittent  quantities,  90;  neces- 
sary in  water,  59 ;  not  added  by  certain 
plants,  65;  reduced  by  sewage,  17. 


Panther,  15,  238,  242. 

Partridge,  196. 

Perch:  pirate,  120;  yellow  or  American, 
85,  99,  119,  120,  126,  130,  156;  trout- 
perch,  84. 

Pest  species,  number  of,  on  different 
forest  trees,  166. 

Pewee,  wood,  242,  244. 

Phalangids,  167. 

Physiological  agreement  of  communities: 
34;  life  histories,  33;  proportionaUty 
in  organisms,  26. 

Physiological  equihbrium:  26;  distrib- 
uted by  changes  in  the  organism,  30, 
by  external  conditions,  30;  in  relation 
to  habitat,  31. 

Pickerel,  grass,  105,  115,  142,  156. 

Pike:  85,  115,  120,  140;  pike-perch,  85; 
wall-eyed,  85. 

Pintail,  171. 

Planarians,  in  Lake  Michigan,  77. 

Plankton:  in  arctic  seas,  66;  proportion 
to  denitrification,  66;  relation  to  tem- 
perature, 66,  to  CO2,  67,  68,  to  oxygen, 

67,  68,  to  carbonates,  67,  68,  to  rate  of 
flow,  67,  to  seasons,  67,  to  age  of  ponds, 

68,  to  moon,  67. 

Plants,  aquatic:  in  sandy  riffles,  99;  in 
sluggish  streams,  104;  value  of,  to 
animals,  65,  142;   watercress,  93. 

Plants,  aquatic,  scientific  names: 

— Chara,  64,  65,  74,  142,  145,  148. 

— Cladophora,  64,  74. 

—Elodea,  65,  129. 

— Eqidsetum,  65,  151. 

— Myriophyllum,  65,  129,  130,  131,  145. 

— Nostoc,  74. 

—Potamogeton,  145. 

— Proserpinaca,  151. 

Plants,  terrestrial,  scientific  names: 

— Arabis  lyrata,  228. 

— Citrus,  257. 

— Gossypium,  257. 

— Hibiscus,  189. 

—J uncus  balticus,  173. 


— Mouarda,  228,  232. 

— Opimtia,  255. 

— Parnassia  caroliniana,  182. 

— Pinus  banks iana,  228. 

• — Sagittaria,  175. 

• — Tilia,  257. 

Plover,  piping,  180. 

Polyzoa,  scientific  names: 

— Fredericella  sultana,  84. 

— Paludicella  ehrenbcrgii,  84. 

— Pectinatella  magnifica,  128,  130,  135. 

—Plumatella,  84,  103,  121,  131: 
polymorpha,  135. 

Polyzoan,  gelatin-secreting,  128,  129. 

Pond  animals  in  streams,  102,  103. 

Pond  communities:  136-57;  temporary, 
173-80. 

Ponds,  vernal  or  temporary:  forest,  179; 
snails  of,  192;  influence  of  rainfall  on, 
177-79;  vegetation  choked,  174;  yoimg, 
with  bare  Wtom,  173. 

Porcupine,  Canada,  196. 

Prairie  chicken,  167,  289. 

Prairie  communities,  278-98. 

Pressure  of  water,  64. 

Protected  situation  of  large  lake,  com- 
munities of,  80. 

Protection  of  wild  animals:  8-1 1;  pro- 
tected species,  56,  57;  wardens,  57. 

Proteid,  foodstuffs,  66. 

Protozoa:  129,  130;  anaerobic,^  133; 
as  animal  food,  20;  producers  of  disease, 
20. 

Protozoa,  scientific  names: 

— Actinophrys  sol,  75. 

—  Diffliigia: 

globulosa,  75. 
pyriformis,  132. 

• — ■Peridinium  tahulatum,  75. 

Psocus,  234. 

Pulmonate    snails,    aquatic    respiration 

of,  129. 
Pumpkin-seed,  84,  156. 
Puss  caterpillar,  behavior  of,  232. 

Quantity:  of  larger  animals,  69;  of  life 
on  land,  166;  of  plankton:  causes  of 
fluctuations  in,  72;  in  different  bodies 
of  water,  67;  in  ponds  of  different 
ages,  69;  in  polar  regions,  66 ;  seasonal 
variation  in,  67. 

Rabbit:    196;   cottontail,  269,  275. 
Raccoon:    199,  202;   eats  crayfishes,  90. 


358 


ANIMAL  COMMUNITIES 


Rail:  king,  171;  sora,  171;  Virginia,  171. 
Rapids:     communities    of    intermittent, 

87;   formation  of,  94-99. 
Rattlesnake,  167. 

Reactions:    defined,    26;     positive    and 
negative,  26;    to  current,  34,  91,  95, 
loi,  106,  107. 
Red-legged  locust,  266. 
Redstart,  274,  275. 
Regulation  in  behavior,  29. 
Rejuvenation  of  streams,  108. 
Relations  of  communities,  308-15. 
Reptiles:    economic  value  of,  10,  21;    in 

timber  and  prairie,  15. 
Reptiles,  scientific  names: 
— Cnemidophonis  6-lineatus,  227,  252. 
— Coluber  constrictor,  255. 
— Crotaliis  diirissus,  237. 
— Hctcrodon  platirhinos,  255. 
— Liopchis  vernal  is,  289,  299. 
— Sistritrus  calenalus,  204,  289. 
—Thamnophis,  150: 

radix,  283,  288,  296. 
— Tropidonotus  grahamii,  283. 
Responses,  to  day  and  night,  to  weather, 

to  seasonal  changes,  31. 
Rheotaxis:  Allee  on,  327;  Lyon  on,  loi; 
of  fishes,  34,  91,  92,  95,  loi ;  of  isopods, 
92;    of  moUusks,  106,  107;    of  stream 
animals,  91,  loi. 
Rivers,  drowned  and  sluggish,  102,  103. 
Roadsides,  13,  275. 

Rotifers:    65;    diurnal  migration  of,  77; 
of  Lake  Michigan,  75-77;   sessile,  131. 
Rotifers,  scientific  names: 
■ — Dlnocharis  tetractis,  84. 
— Notops: 

pelagiciis,  76. 
pygmaeiis,  77. 
— Rotifer  elongatus,  84. 
Roundworms,  in  Lake  Michigan,  77. 

Salamanders:  four-toed,  237;  spotted, 
149,  278,  282,  296;  sticky,  181,  183, 
207;  red-backed,  197,  243,  255. 

Sandpiper,  spotted,  180,  181. 

Scorpion-flies,  202. 

Scorpion-flies,  scientific  names: 

— Bittaciis,  202: 
strigostis,  208. 

— Panorpa,  40,  191 : 
venosa,  200,  208. 

Seasons:  Relation  of  animals  to,  31; 
succession  with,  36,  278;  quantity  of 
plankton  in,  67. 


Sediment,  in  water,  relation  to  light  pene- 
tration, 63. 

Seeds,  as  animal  food,  167. 

Segregation  of  species,  vertical  in  Lake 
Michigan,  82. 

Seines,  illegal,  57. 

Selection  of  habitat:    300-305;    law  of 

toleration  in,  302-5. 
Sessile  animals,  food  of:   97;   in  sea,  309; 

motile  animals  compared  with,  309. 
Sewage,  effect  of:   upon  stream  animals, 

17;    upon  oxygen  content,   17;    upon 

plankton,  17. 

Sheepshead,  85. 

Shiner:    79,  84;    common,  115,  119,  120, 

140;  golden,  65,  102,  115,  119,  120,  142, 

143,  156. 
Shore-bugs,  180. 

Shores,   sandy:    of  large  lakes,    78;    of 

small  lakes,  125,  126. 
Shrew:  common,  189,  191,  196,  201,  262, 

269,  274;   short-tailed,  201. 
Shrike,  loggerhead,  275. 
Shrimps,  scientific  names: 
— Eubranchipiis,  177,  178,  179,  278: 

serralus,  185,  279. 
— Palaemonetcs  pahidosus,  126,  130,  135, 

152. 
Silv-ersides,  85,  130,  135. 
Skunk,  12,  15,  169,  199,  262,  274. 
Slug  caterpillar,  233. 
Slugs,  scientific  names: 
— Agriolimax  campestris,   199,   200,   202, 

205,  236. 
• — •Pallifera  dorsalis,  256. 
— PhilomycHs  carolincnsis,  206,  215,  240, 

241,  243,  247,  253,  254. 
Smeared  dagger-moth,  larva  of,  190. 
Snails:  aquatic,  90;  in  lakes,  130;   reac- 
tions of,  to  fight,  29;    reactions  of,  to 
water  current,  34. 
Snails,  aquatic,  scientific  names: 
— Amnicola,  80,  148: 

cincinnaticnsis,  117,  154. 

emarginata,  83. 

limosa,  85,  gg,  117,121,  145,  146,154. 

limosa  parva,  154. 

limosa  porata,  83. 

liistrica,  83. 

walkeri,  84. 
— Ancylus,  130: 

fuscus,  135. 

rivularis,  121. 

tardus,  121. 
— Aplexa  hypnorum,  192. 


INDEX  OF  SUBJECTS 


359 


Snails — Continued: 

— Campcloma,  99,  103,  104,  106: 

integrum,  107,  108,  117,  123. 

subsolidum,  100,  117. 
— Goniobasis,  103: 

livescens,  95,  98,  103,  116,  121,  123, 

126,  135. 
— Lymnaea,  84,  104,  131,  145: 

exigua,  173,  185. 

lanceata,  85. 

modicella,   114,    121,    154,    174,    i8r, 

186,  187. 

obrussa,  154. 

reflexa,  147,  149,  i54,  i74,  175-  185, 

189. 

reflexa  exilis,  154. 

stagnalis,  83. 

woodruffi,  79,  80,  84. 
—Physa,  145-151: 

gyrina,  93,  114,  118,  121,  131,  135, 

154,  173.  185. 

heterostropha,  154,  173. 

Integra,  104,  117,  131. 
— Planorbis,  173,  185. 

bicarinatus,  39,  83,  99,  104,  117,  121, 

123,  154- 

cainpanulatus,  114, 131,  135,  147,  149, 

154- 

deflectus,  154. 

exacuosus,  154. 

exacutus,  83. 

kirsutus,  148,  149,  154. 

^arar5,  116,  131,  135,  148,  149,  154, 

204. 

irivolvis,  16,  149,  150,  152,  154. 
— Pleurocera,  99,  103: 

elevatum,  106,  107,  108,  121,  123. 

ekvatum  lewis ii,  117. 

subulare,  39,  126,  127,  135. 

subularc  intensum,  121. 
— Pleuroceridae,  84. 
— Segmentina  armigera,  131,  135,  154. 
— Valvata,  80: 

Mcarinata  perdepressa,  83. 

sincera,  83. 

tricarinata,  83. 
— Vivipara  eontectoides,  126,  128,  152. 
Snails,  hibernation  of,  192. 
Snails,  terrestrial,  scientific  names: 
— Circinaria  concava,  200,  204,  206,  237. 

253- 
— Omphalina  fuliginosa,  253. 
— Polygyra: 

albolabris,  197,  207,  215,  237,243,254. 

clausa,  200. 

fraudulcnta,  243,  256. 

in  fleet  a,  234,  256. 

monodon,  190,  213,  215,  254,  263. 

multilineata,  206,  234. 


opprcssa,  243,  256. 
palliata,  243,  256. 
pennsylvanica,  236,  237. 
profunda,  200,  202,  215,  236,  237. 
thyroidcs,    200,    202,    208,    213,    215, 
234,  252,  254. 
— Pyramidula,  214,  215,  243: 

alternata,  192,  200,  236,  237,  243,  247, 

253,  254. 

perspectiva,  256. 

solitaria,  236,  237,  243,  256. 

striatcUa,  190. 
— Suceinea: 

avara,  187,  199,  202,  208,  282. 

ovalis,  208,  263,  264. 

retusa,  169,  187,  189,  199,  202,  204, 

208. 
— Vitrea  indcntata,  205. 
— Zonitoides,  215: 

arboreus,  190,  206,  234,  236,  243,  247, 

253,  306. 
Snakes,  food  of  skunks,  269. 
Soil:    157-59;    effect  of,   on  organisms, 
159;      factor     in     distribution,     301; 
humus,  158-59. 
Sowbugs   or   Isopoda,  aquatic,  scientific 

names: 
• — Asellus   eommunis,   90,   98,    114,    121, 

154,  174.  185,  206. 
— ManeaseUus  danielsi,  135,  154,  174. 
Sowbugs,  terrestrial,  scientific  names: 
— Cylistieus  convexus,  239,  253. 
— Porcellio  rathkei,  200,  240,  254,  253. 
Sparrow:   chipping,  274,  275;   field,  274, 
275;   grasshopper,  167,  289;   lark,  275; 
song,  262,  268,  275;   vesper,  167. 
Sparrow-hawk,  274. 
Species,  animal:   i;  number  of,  i;  plant, 

i;  use  in  ecology,  3. 
Sphaeridae,  scientific  names: 
— Calycidina  transversa,  83. 
— Musculium,  118,  179,  189. 

partumeium,  147,  153. 

sceurc,  147,  153,  185. 

truncatum,  121,  147,  153. 
— Pisidium,  81 : 

compressum,  83. 

idahoense,  83,  133. 

punctatum,  83. 

scutellatum,  83. 

variabile,  83. 

ventricosurn,  83. 
— Sphaeridae,  69,  80,  83,  100,  103,  147, 

151,  153- 
— Sphaerium,  108: 

stamineum,  107,  116,  121. 
striatinuni,  80,  83,  116. 
vermontanum,  79,  84. 


36o 


ANIMAL  COMMUNITIES 


Spherid,  anaerobic,  133. 
Spiders,  167. 
Spiders,  scientific  names: 
■ — Acrosoma: 

gracilis,  238,  240,  260. 

spinca,  238,  240,  260. 
— Agelcna  naevia,  207,  218,  254,  296. 
— Anyphacna  conspersa,  260. 
— Argiope: 

aurantia,  263,  264,  276,  296. 

trifasciata,  204,  205,  208,  232,  259, 
263,  293,  296,  298. 
— Atlas  paluslris,  276. 
— Alypiis  milberti,  277. 
— Caslianeira  cingulata,  197,  207. 
— Chiracanihium  inclusa,  187,  205. 
— Clubiona  obesa,  277. 
—Dendryphanles: 

mililaris,  205,  206. 

oclavus,  204,  205,  206,  228,  258. 
— Dictyna: 

Joliacea,  206,  208,  228,  232,  257,  276. 

siiblata,  187,  204,  207. 
— Dictynidac,  257. 
— Dolomedcs: 

sexpunclatus,  146,  169,  187,  283,  296. 

lencbrosus,  243. 
—Epeira,  198,  232: 

domicilorum,  240,  257,  306. 

foliata,  187,  204,  206. 

gigas,  194,  205,  206,  208, 240,  257,272. 

ocellata,  206. 

prom  pi  a,  204. 

trifolium,  205,  276,  277,  296. 

Irivillata,  188,  205,  214,  276,  284,  293, 

296. 
— Epciridae,  208,  257,  260. 
— Eucta  catidala,  187. 
— Eugnalha  slratninea,  204,  296. 
— Gayenna  ccler,  260. 
— Gcolycosa  pikei,  220,  227,  230,  250,  252. 
—Habroccslum  piclex,  206. 
— Hypsel isles  florens,  207. 
— Leucatigc  horlorum,  202,  208. 
— Liiiyphia  phrygiana,  260. 
— Lycosidac,  261. 
— Maevia  niger,  260,  277,  298. 
— Mangora  maculata,  206,  260. 
— Misiimena  vatia,  214,  264,  285,  296. 
— Misumcssus: 

asperalus,  231,  232,  257,  293. 

oblongus,  207. 
— Nolionella  interpres,  261. 
— Ozyplila  conspurcala,  296. 
— Pardosa,  215: 

lapidicina,  213,  214,  215.  254. 
— Phidippus: 

aiidax,  207,  264, 

horeaUs,  297. 


podagrosus,  204,  293,  298. 

rufus,  298. 
— Philodroimis: 

alaskensis,  223,  228,  257. 

ornaius,  205. 

pernix,  259. 
— Pirata: 

insularis,  187. 

montana,  204. 

piratica,  206. 
— Pisauridae,  204. 
— Pisaiirina,  198: 

undata,  204,  206,  208,  277^ 
— Plectana  slellata,  204. 
— Rimcinia  alealoria,  204,  214,  277,  293, 

296. 
— Singa  variabilis,  276. 
■ — Telragnatha: 

grallator,  205,  206. 

laboriosa,   169,   187,   208,   263,   276, 

284,  285,  296. 
— Theridiidae,  257. 
— Theridium: 

frondeum,   191,   202,   206,   20S,   240, 

257,  258. 

spirale,  228,  258. 
—Thiodina  puerpera,  204. 
— Thomisidae,  257. 
— Tibellus  duttoni,  187,  204. 
—Trochosa  cinerea,  222,  252. 
— IT'a/a  mitrala,  261. 
— Xyslicus  formosus,  228,  258. 
— Zygoballus  bcttini,  206. 
Spittle  insects,  habits  of,  202. 
Sponge,  abundant  in  stream,  97. 
Sponges,  scientific  names: 
— Heleromeyenia  argyrosperma,  153. 
— Meyenia: 

crater  if  or  mis,  153. 
fliiviatilis,  153. 
■ — SpongiUa,  116,  131: 

fr'agilis,  153. 
Spontaneous  movement,  26. 
Springtails,  180. 

Squirrels:      233;      fox,     245;      Franklin 
ground,  269,  274;   gray,  192,  202,  245; 
ground,  167,  227,  286;   red,  245. 
Stations  of  study,  50,  51-56. 
Statoblast,  129. 
Stickleback,  85. 
Stimulus,  defined,  26. 
Stinkbugs,  hibernating,  202. 
Stonecat:   119;   slender,  95. 
Stone-fly  nymphs,  scientific  name: 
— Perla,  78,  116,  121. 
Stone-roller,  119,  120. 


INDEX  OF  SUBJECTS 


361 


Stones:  in  water,  78,  88,  95-97;  currents 
about,  61. 

Strata:  defined,  37;  in  aquatic  vegetation, 
105;  in  rapids,  94-96;   on  land,  165. 

Stream  communities:  78,  86-123;  base- 
level,  102-5;  intermittent,  87-92; 
longitudinal  arrangement  of,  108-23; 
sandy,  101-2;  sluggish,  102-5;  spring- 
fed,  93;   swift,  93-99. 

Struggle  for  existence,  5-6. 

Sturgeon,  85. 

Succession:  autoproductive,  308;  causes, 
308;  defined,  36;  ecological,  36; 
forest,  247-50;  geological,  36;  lake, 
135;  pond,  152;  seasonal,  35,  36, 
278;  stream,  110-13. 

Sucker:  carp,  85;  chub,  115,  119,  142, 
156;  common,  84,  91,  92,  106,  115, 
119,  120;  long-nosed,  84;  hog  or  stone- 
roller,  84,  119;  red-horse,  84,  115,  119, 
140;   short-headed  red-horse,  120. 

Sunfish:  bluegill,  84,  99,  115,  119,  120, 
126,  156,  141;  blue-spotted  or  green, 
102,  119,  120,  126,  128,  156,  141; 
long-eared,  99,  119;  pumpkin-seed, 
126,  156,  141. 

Swallow:  bank,  222;  tree,  225. 

Swamp  communities,  169-73,  189-97. 

Tadpole  catfish,  85,  105,  119,  142. 

Tamarack  swamp  commvmities,  193-97. 

Tanager,  scarlet,  244. 

Taxis,  26,  27. 

Temperature:    of   soil,    158-59;   habitat 

compared,  159;  control  of  distribution, 

199-304. 
Temporary  ponds,  173-80. 
Tension  Unes  between  land  and  water, 

169-88. 
Terminology  of  ecology,  36-38. 
Termites,  220-22. 
Termites,  scientific  name: 
—Termesflavipes,  220,  252. 
Tern,  black,  170. 

Terrestrial  conditions,  169-88,  247-50. 
Thicket  communities,  262-75. 
Thrush:  hermit,  195;   wood,  241,  244. 
Thysanoptera,  306. 
Tiger-beetles,  180,  216;  larvae,  210,  214, 

216. 
Toad:    167,  187,  283,  296;    daily  habits, 

222. 
Toadbug,  180. 


Toleration,  law  of,  302-5. 

Tolleston  beach,  47. 

Top  minnow,  84,  120,  123,  132,  135. 

Toxic  substances,  in  soil,  159;  in  water, 
331  (114,  1140). 

Transparent  animals,  77. 

Tree-fauna,  differs  with  surrounding 
conditions,  16,  251. 

Trespass  laws,  56. 

Tropism,  26,  27. 

Trout,  Mackinaw  or  Lake,  59,  78,  79, 
80,  82,  85. 

Turkey,  wild,  14. 

Turtles:  geographic,  130,  135,  156; 
habits  of,  130;  musk,  126,  130,  135, 
142,  156,  breeding  of,  130;  painted, 
132,  156,  227;  protected  by  law,  57; 
snapping,  132;  soft-shelled,  130;  trans- 
portation of  animals  by,  173. 

Turtles,  scientific  names: 

— Aromochelys    odorata,    126,    135,    142, 

156. 
— Aspidonectes  spinifer,  130. 
— Chrysemys  marginal  a,    132,    156,   227. 
— Graptemys  geographiciis,  130,  135,  156. 

Upstream  migration:  of  fishes,  106;  of 
moUusks,  106. 

Valparaiso  Moraine,  46. 

Variation  of  behavior  and  habits  related 

to  conditions,  34. 
Varying  hare,  15,  191,  195. 
Vegetation:     aquatic,    65    {See   Plants); 

climatic,  49,  50,  51,  174. 
Vernal  fauna,  173-80. 
Vertebrata,  2. 

Vertebrates,  products  from,  21. 
Vireo,  red-eyed,  196,  244. 

Warbler:  black,  241;  blackburnian,  196; 
black-throated,  229;  green,  229;  pine, 
229;  prothonotory,  190,  191;  yellow, 
196,  241,  274,  275. 

Water  in  soil,  157-58. 

Water  margin  communities:  180-83; 
sedge-covered,  181;  shrub-covered, 
181;  terrigenous,  of  large  lakes,  180, 
of  ponds,  180,  of  rivers,  181. 

Water  scavenger  beetles,  65. 

Water-scorpions,  65,  104,  123,  131,  151, 
155- 

Water- striders:   90;   hibernation  of,  201. 


362 


ANIMAL  COMMUNITIES 


Water-striders,  scientific  names: 
— Gerridae,  185. 
— Gcrris: 

marginalus,  155. 
rufosciiteUatus,  155. 
— Mesovelia  bisignala,  155. 
— Rhagovdia  collar  is,  98,  117. 
Weasel,  201. 
Weeds,    avoided    by    aquatic    animals 

during  flood,  105. 
Weevils,  167. 

Wheel  animalcules.     See  Rotifers. 
Whitefish:   76,  77,  82,  85;  blackfin,  81, 

82;    Hoy's,  81,  82,  85;    long-jaw,  79, 

80,  82,  85. 

WiUow    blossoms,     visited    by    pollen- 
gathering  insects,  224-25. 
Willow  sawfly:   large,  267;   spotted,  267. 
Wildcat,  242. 
Wilting  coefficient  of  soil,  158. 


Wind:  influence  on  circulation  in  lakes, 
61;  relation  to  light  penetration,  63, 
to  evaporation,  160,  162,  163. 

Wolf,  15,  167,  201,  236,  238,  245. 

Wood  pewee,  196,  244. 

Wood  thrush,  241. 

Woodchuck,  215,  233,  236. 

Woodcock,  189,  191. 

Wood-frog,  244. 

Woodpeckers:  196,  274;  downy,  229; 
in  beach  drift,  219;  red-headed,  242. 

Worms:  flat,  20;   round,  20. 

Wren:  long-billed  marsh,  171;  short- 
billed  marsh,  181. 

YeUowlegs,  181. 

Yellowthroat,  northern,  189,  262,  275. 

Zonation  in  forest  edge,  263. 


'">  f»ROPERTY  OF 

Z.  P.  METCALF 


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